The $100K/Month App Hiding in Plain Sight in TikTok Comments

Do you remember being 14 years old, staring at the ceiling, and wondering if you were ever going to grow tall enough? That primal, suffocating anxiety of puberty—the fear that biology had already decided your fate and you were just waiting to find out how badly you got screwed.

Most of us suppress that memory. Michael Que monetized it.

Last year, Michael was a typical NYU Stern student knocking on the doors of Wall Street, only to get rejected by Goldman Sachs and endless other firms. He took an unpaid internship, hated it, and quit. But while he was failing at the traditional finance path, he noticed something: kids half his age were making hundreds of thousands of dollars a month off incredibly simple mobile apps.

So he went looking for a problem to solve. He didn’t brainstorm in a vacuum. He didn’t try to invent a revolutionary AI feature. He went to the TikTok comment sections.

That’s where he found thousands of teenagers leaving their height, their parents’ heights, and their ages, desperately asking one question: “How tall will I be?”

From that single, anxiety-ridden question, he built GoTall. Within a year, it hit a million downloads and crossed $100,000 in monthly recurring revenue.

But to understand why this app prints money, you have to look past the surface. GoTall looks like a height prediction calculator. You input your data, and it spits out a number.

If it stopped there, it would just be a boring web tool. But Michael understood a fundamental truth of consumer psychology: The most lucrative products don’t solve practical problems; they exploit anxieties you can’t control.

GoTall isn’t a calculator. It is an anxiety-management and gamification engine disguised as a utility. The prediction is just the top-of-funnel bait. The actual product is the infinite loop of tracking and habit-forming built around a biological process you cannot change.

Michael didn’t just guess this would work. He validated it ruthlessly. Most founders write code first and look for users later. Michael did the opposite. He went to Acquire.com, a marketplace for small internet businesses, and found that someone had already built a basic height prediction app and was selling it for $20,000.

That was his second layer of validation. It wasn’t just that kids were asking questions on TikTok; someone had already proven people would pay for the answer.

He built the app. It got its first paid user in 48 hours. Stop writing code for hypothetical problems. Go mine the public platforms where desperate strangers are already screaming for a solution.

But having a good product isn’t enough. You still have to acquire users. Michael tried ads; they failed. He tried influencers; they were too expensive. He was living in Jersey City, borrowing NYU’s campus as an office, and posting 20 TikToks a day to crickets.

Then he found the twist that made it viral.

He stopped making “content” and started directly replying to TikTok comments. Someone would comment: “14 years old, 173cm, dad 183cm, mom 165cm, how tall will I be?” Michael’s account would use TikTok’s reply feature, pin the comment to a video, and give them a prediction.

The loop was vicious. The question was hyper-specific. Other kids the same age would see it, project themselves onto it, and immediately comment their own stats. The comments became an infinite, free content engine.

He didn’t hire mega-influencers. He direct-messaged dozens of normal creators and paid them $5 a video to follow his exact, proven format. By December, he had millions of views, and his revenue jumped from $30K to over $100K a month.

But here is where the story gets dark, and where the real lesson lies.

Michael quickly noticed that users didn’t just predict their height once. They came back every week. They tracked their sleep, scanned their food, and updated their profiles, just to recalculate the number. It was like a slot machine—they kept pulling the lever to see what number they would hit this time.

So he gamified it. He added AI coaching, daily streaks, and a community. He turned a one-time calculator into a Duolingo-style retention engine. In business, anxiety is the ultimate retention mechanism. In ethics, it’s a psychological crisis waiting to happen.

Because GoTall’s user base isn’t just random consumers. It’s vulnerable teenagers. An algorithmic error that tells a 14-year-old boy he will only grow to 5’5″ isn’t just a bug. It’s a blow that can shatter their confidence for years.

Michael admitted this himself. He had to build Discord servers to talk to users directly and rework his prediction logic because early errors were causing real psychological damage. The paradox of his success is undeniable: the more anxious the user, the more they check the app; the more they check the app, the higher the monetization. It is a moral hazard built directly into the code.

But love it or hate it, the framework is undeniable. The best product opportunities on the internet aren’t hiding in complex codebases or undiscovered technologies. They are hiding in plain sight.

They are in the TikTok comments, the Reddit threads, and the search queries where people are already actively exposing their private data and begging for an answer.

If people are already spending hours searching for a solution to a problem, it’s no longer just a content topic. It’s a product demand. Stop inventing. Start listening.