Four Failed Startups and a Cancer Diagnosis: David Park on Building Jenni AI

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Overview

David Park, 27, is the CEO of Jenni AI, an academic AI assistant that helps with research, writing, and "everything in between." In this interview, Park recounts eight years of startup failure before Jenni began to grow, and then a thyroid cancer diagnosis shortly after. The question running through the conversation is why a founder keeps going through years of little visible progress. Park's answer is partly practical, centered on talking to users relentlessly and taking responsibility seriously. It is also partly personal: "You can always fail. You can fail at something you don't love. So, you might as well fail at doing what you love."

17 min read

Where Jenni AI Stands Now

Park opens with the company's current numbers. According to Park, Jenni has raised money from Jason Calacanis and from the AI Grant, run by Nat Friedman and Daniel Gross. Park says the company has grown about 15 to 20% per month for the last 10 months, is at roughly $2.5 million in annual recurring revenue, and has over 2 million users globally. Park believes there are now Jenni users in every country in the world.

Park grew up in a family that "wasn't rich." Park credits their parents with giving them a lot of love and confidence, which let them "believe in myself and do crazy things like start a company."

The First Business: A High School Clothing Brand

Park's first venture, at 16, was a clothing brand sold to students at their high school and neighboring schools. It failed "pretty spectacularly," and Park lost all their money. Looking back, Park says they didn't know the basics of business and naively believed that building something cool was the most important thing. It's not enough, in Park's words, "to just make a t-shirt" and assume you'll become a millionaire.

Still, that brand gave Park what they call the coolest moment of their life. At a mall, Park saw a tall, athletic "jock kind of guy," someone who would never have been their friend, wearing one of the sweaters they had made. The thought that something they built was valuable enough for that person to choose to wear it stuck with Park. Park traces their lasting interest in making products that provide value to people back to that moment.

Dropping Out After a Pitch on a Plane

Park attended UC San Diego. On a flight from Seattle to San Diego, Park noticed that the passenger next to them had Coinbase open and guessed he was "probably pretty rich." For the next three hours, Park says, this passenger was their "captive prisoner," and Park kept pitching their startup idea. Park thinks he was annoyed, but that he also recognized how much Park cared about what they were building. Less than three days after landing, they met up, and he handed Park a cashier's check, Park's first investment ever. Park then dropped out of college and went full-time.

A Social App and an AI Dating App

The next venture came from a college observation. People Park met kept saying "add me on Snapchat," "add me on Instagram," or "here's my LinkedIn." Park's team built an app that would add someone across Instagram, Facebook, Snapchat, and LinkedIn with one button. It didn't do well. Park lists the reasons: they didn't know how to acquire customers, didn't understand network effects, weren't building for their users, and made "a lot of poor decisions product-wise."

Then came an AI dating app, which Park still considers "actually pretty cool." Users didn't swipe. Instead, the system used machine learning to analyze a user's face and their previous partners to predict physical attraction, and looked at their Facebook to infer interests. The company partnered with restaurants in the city and set up the first date at a restaurant both people liked, with a coupon. Park describes it as a concierge service, and says local businesses loved it because it brought them free customers.

It ended when Park tried to raise money. According to Park, a VC declined because the investor wanted users to stay on a dating app as long as possible. If users found a partner and became happy, they would delete the app and stop paying, and it would never become a billion-dollar business. Park, around 19 or 20 at the time, found this "really sobering," like crossing "the chasm into like the adult world of venture capital." Park was disillusioned, and the team stopped working on the product.

Failure Feels Different After Dropping Out

Park distinguishes between failing in college and failing afterward. The first failure "didn't feel that bad" because Park was still a student. Once they had dropped out, failure brought real pressure. Park would see friends on Instagram posing in graduation gowns while Park lived with their parents or worked on a startup that wasn't going well. A year later, those friends had high-paying jobs at companies like Microsoft, and Park was in the same place. Park says they tried not to compare themselves with others, but "you can't have full control over your mind." This is the context for the line about failing at what you love. Failure was possible either way.

Setting Aside Ego and Gut Instinct

The most valuable lesson from this period, Park says, is that gut instinct "rarely provides me much value." Park's image for it: the blueprint for a billion-dollar company is "ripped up and scattered among minds and actions of the users" you are building for. A founder needs to be egotistical enough to believe they can build a billion-dollar company, which Park calls "a wild statement," and humble enough to recognize they don't know much and must keep talking to users. Once a founder puts ego down, Park thinks, a startup can "blossom a lot better."

Jenni's Origins: GPT-2 and a Strange Sentence

Park majored in literature and loved poetry and writing. Their co-founder was a computer science engineer who later did a PhD in natural language processing. The two wanted to connect writing and AI.

They started Jenni when only GPT-2 existed. While experimenting, they got a generation Park still remembers: "Nothing is darker than a butt hole." Park found it the funniest thing they had ever read, a sentence no human had ever said to them, and at the time also somehow profound. The reaction was that an AI had written this, so they had to find a way to make a business out of it. Park adds right away: "I really don't recommend anybody do this. We just got really lucky."

The first version of Jenni aimed to make human writers about 10% faster using GPT-2. The team brought writers into the office and timed them with and without AI, targeting 10%, 15%, then 20% speed improvements. When GPT-3 arrived, they realized it could produce genuinely useful text. That's when they moved from an agency model to SaaS. They no longer needed human writers, and Jenni became a general tool that anyone could use, "like Microsoft Word, but AI first."

Getting Better by Removing Features

Park describes a counterintuitive pattern: as the team removed features, Jenni kept improving, and each round of "ripping things out" made the vision clearer about what people actually came for. The team focused on time to value. The question they asked was whether a new user could get their first autocomplete within the first five minutes.

Early customers came through direct effort. Park cold-called businesses, talked with them, became friends with them, and tried to figure out how to deliver the best product. The team talked with the few users who arrived, tweaked the tool, relaunched, and repeated. Eventually a large wave of users came in, and nearly all of them were students. The team chose to keep building for researchers and people in academia, since they were the ones getting value from the tool.

How Park Talks to Users

Park argues that money matters far less in the early stages than it seems to a struggling founder, especially one trying to build a big company. If someone will talk to you and try your product, giving them a month or two free is "no problem at all." Park criticizes founders who refuse to give anything away as "a little arrogant." In Park's view, the lifeblood of a startup is knowing what to build. Continuous user conversations make gut instincts faster and product sense better. Park's main tip is to prioritize talking to users above everything else, including money.

Park also advises asking uncomfortable questions. With only 10 users, a phone call with one of them is rare, and you don't know when the next one will come. Asking "What's your favorite thing about my product?" only makes the founder feel slightly better and yields no information. Park instead recommends asking what the user's current workflow looks like and what their biggest pain point is. When relevant, founders should ask about the product's bad points rather than its good ones. Users try to be polite, Park says. Some will lie outright, and some will lie without realizing it. So founders have to judge heavily by users' actions. Park's view is that you get more comfortable only by repeatedly putting yourself in uncomfortable situations.

A Tiny Podcast and a $100K Check

An early-stage startup "has nothing going for you," Park says, so you take any call. While struggling, Park even replied to spammy LinkedIn messages obviously sent to a thousand people. Park was invited onto a podcast with very few listeners. One of them happened to be a scout for Jason Calacanis. The scout emailed about a possible investment. Park missed that first email, but the scout sent a second one, Park replied, and they invested $100,000.

Park went to their grandfather's house and the family was "swearing in Korean" in disbelief. Park had never seen that much money, took a screenshot of it, and stared at it constantly.

Going to Malaysia to Survive

The business wasn't doing well when the check arrived. Park recalls revenue of about $2,000 in month one, then $2,200, $2,300, and $2,500, growth Park calls almost negligible. Park didn't fully trust themselves with the money as a young founder unsure of their decisions. So Park and their co-founder flew to Malaysia, where Park says everything costs about a quarter of the price.

As they had predicted, they kept making "amateur decisions." Jenni stayed at roughly $2,000 MRR for another one and a half to two years. Park believes that if they hadn't gone to Malaysia, the company would have died before it started growing.

The Lost $250K in Korea

During that stretch, Park was invited to the K-Startup Grand Challenge, a competition where top-10 finishers win money. Park went to Korea with the company low on cash and secured a $250,000 investment from a VC that seemed "pretty much a done deal."

The night before the key meeting, Park stayed out very late with a girl they really liked, thinking it would be fine. Back home, Park found a document they needed to fill out, entirely in Korean. Park's Korean is "okay" but not good enough for a legal document, so Park worked through it with Google Translate until around 3 a.m., slept little, woke at 8, and arrived late to the 9 a.m. meeting. That night, the VC emailed to say they would not invest because it wasn't the right fit.

The company was two months from running out of money. Park had a team, including a software engineer whose wife was either pregnant or had just had a baby. Park says they cried hard that day and calls it one of the worst days of their life. Last-minute calls to a VC who had shown interest earlier brought in enough runway to survive.

Park draws a lesson about discipline from this. People become entrepreneurs to avoid the 9-to-5 and live on their own terms, and Park admits they had some of that attitude, thinking VCs were lucky to invest in them. Park now believes founders need to be even more disciplined than someone who shows up to every meeting at a regular job. People who join a startup bet on the founder and could have had prestigious jobs elsewhere. Park's point is that when you take on that much leverage and risk, you have to act like it.

The Viral Thread

One night around 11 p.m., while their co-founder was asleep, Park saw the site "going crazy": with every refresh, about 10 new users arrived per second. Jenni had been included in a Twitter thread that Park describes as the most viral thread in history related to AI or startups. The team had a limited pool of OpenAI credits, which Park recalls as somewhere around 1,000 to 5,000 and a lot at the time. Park says users burned through all of it within an hour.

Park called the co-founder, who didn't wake up, and ended up swearing at them on Slack that this was their big break. Meanwhile Park messaged every visitor through Intercom, asking for emails so they could be notified when service returned, unsure whether this was a one-time spike or something lasting. Park calls it the first real feeling of "some semblance of success." Raising money, in Park's view, never felt like success. It felt like the moment the real work begins.

Park expected the growth to fade and prepared for a slower pace afterward. It didn't stop. Every month, according to Park, the team found some new distribution channel or growth tactic.

The Cancer Diagnosis

About two months after the viral tweet, Park was in Korea and went to get a long-standing growth on their jaw checked. The nurse offered to examine their neck as well. Park says you know things are bad when the nurse suddenly goes quiet. She told Park there was a 50% chance of thyroid cancer because of tumors in the thyroid. Park didn't believe it at first. A life without cancer was all they had ever known. Then an email from the doctor confirmed the diagnosis.

Park recalls a quote: "a tree can't reach heaven unless its roots reach hell." After eight years of startups with nothing to show for it, Park had finally peeked "a little bit above the clouds," and then came cancer.

Before surgery, Park tried to raise money so the startup wouldn't die if they did. Park believes VCs "could smell the desperation," especially since Park needed the money wired within the month.

The Day of the Surgery

On the day of surgery, the doctor said Park had a fever and asked whether to reschedule. Park decided to proceed, reasoning that there would always be some reason to delay. Park's temperature kept rising, and nurses covered them in ice packs. Park's mother sat beside them and said that before surgery she would tell Park something that would give them all the strength they needed.

She stepped out briefly, and at that moment nurses rushed in: an operating table had opened up and surgery had to happen now. Park's mother wasn't there. Park was afraid of not understanding instructions, knew the fever raised the risk, and wanted to leave. But on the waiting room ceiling was a Bible verse about not being afraid and leaving everything up to God. The surgery went well.

A few days later, once Park could speak again, they asked their mother what she had meant to say. It was a Bible verse she had found online, the same one that had been on the ceiling. Park says they are not very religious, but it prompted a reflection on how much of their life has felt miraculous: sitting next to their first investor on a plane, Jason Calacanis investing because of an obscure podcast, a viral tweet from a stranger, and getting cancer. Park says they now feel grateful for their "little miracles every day."

The Unglamorous Reality

Park closes by pushing back on how startups have been romanticized, pointing to Netflix-style dramatizations of companies like Theranos and Uber. Most startup work, Park says, "is not very sexy." It means putting in the work day after day and figuring out what matters most. Sometimes that means opening a spreadsheet, finding a relationship in the numbers, and using it the next day to make a product decision. These scenes never appear in movies.

Park restates the opening point: "The sad truth isn't that you'll fail." Park believes that anyone who builds a startup over a long enough time horizon can probably make something and earn some kind of living. The sad truth is that many days will be really boring. Park compares their present with their past. Today there is some fire every day, along with constant major decisions about spending, hiring, partnerships, and whose check to take. None of it is as painful as the old dread of sitting alone in their room, "staring into the void," doing boring tasks with no idea what to do and nothing happening. Park's closing advice is to be ready for many years of putting in the hours and the reps.