How a 20-Year-Old Built a $100K/Month App from a TikTok Comment

Most people scroll past TikTok comments. Michael Que read them like a business plan.

At 20 years old, still a finance student at NYU, Michael built GoTall — a height prediction app for teenagers — and scaled it to roughly $100,000 in monthly recurring revenue. Around 1 million downloads across the App Store and Android. Over $434k in sales since January alone, according to his App Store Connect data. And it all started with a comment section.

Let's break down exactly how he did it.

Step 1: Turn Rejection Into Motivation

Michael was recruiting hard for finance jobs. Investment banking, the usual dream for NYU finance students. He got rejected from all of them.

Instead of doubling down on applications, he shifted his focus entirely. He noticed startups blowing up on TikTok through smart, repeatable marketing. He'd been building apps since he was a teenager, so the technical side wasn't the problem. Marketing was the missing skill. He made a deliberate decision: find any app idea with potential and treat it as a vehicle for learning growth and distribution. Even if the app failed, he'd come out ahead.

That mindset is underrated. Most first-time founders get obsessed with building the perfect product. Michael committed to learning marketing, and let the product be almost secondary.

Step 2: Validate Before You Build

Michael used a two-pronged validation approach that's simple enough for anyone to copy.

First, browse acquire.com. He found a similar height prediction app listed for sale at around $20,000. That listing alone confirmed there was a real market. Someone had built it, made money from it, and now it was worth something. He didn't need to guess whether the idea could work — the marketplace told him.

Second, look for emotional pain in the wild. Michael recalled searching for "height calculators" on Google when he was 13. Then he went to TikTok and found videos about height absolutely flooded with comments like "how tall will I be?" followed by users listing their parents' heights, desperately trying to calculate their own future. That desperation is the signal. When people are volunteering personal data in a public comment section because they want an answer *that badly*, you've found something real.

The final confirmation? He launched the app and made his first sale two days later.

Step 3: Target Real Human Needs, Not Clever Niches

Michael references Maslow's hierarchy of needs when explaining why GoTall works — and this is probably the most transferable insight in his whole story.

GoTall isn't really about height. It's about esteem — self-respect, status, how others perceive you. And it's about love and belonging — fitting in, being attractive, feeling accepted. These sit right in the middle of Maslow's pyramid, which means they're deeply universal and emotionally charged.

Teenagers are acutely vulnerable on both of those dimensions. Height, for many teenage boys especially, feels tied directly to identity and social standing. That makes the pain point intense, and intense pain points convert.

Michael's broader advice here is that you don't need to invent something original. New calorie-tracking apps launch every month and make real money despite MyFitnessPal dominating the space for years. What matters is whether you're solving a problem that sits close to someone's core sense of self. If the answer is yes, there's room for you.

Step 4: Find Your Repeatable Content Format

Michael's marketing strategy is one of the cleanest organic-to-paid playbooks I've seen from a solo founder.

He started by posting around 10 TikToks per day for a full month — all by himself. Not outsourcing, not guessing. Just experimenting at volume until something clicked. The format that broke through was deceptively simple: reply directly to comments from users asking for a height prediction. TikTok's reply-to-comment video feature lets you stitch the comment right into the video, which feels personal and drives curiosity.

Once he found that format, he didn't just keep doing it on one account. He proved it was repeatable by replicating it on two of his own accounts and then his girlfriend's account. Three accounts, same format, same results. That's not luck — that's a system.

This is the step most founders skip. They find something that works once and scale it immediately. Michael made sure it worked three times before spending a dollar.

Step 5: Scale With UGC Creators, Then Paid Ads

Once the format was proven, Michael started DMing 50 UGC creators per day to make videos using the same reply-to-comment structure — at cheap rates. He wasn't hiring influencers with massive followings. He was hiring people who could execute a specific format at volume.

This organic push scaled GoTall to $10,000/month. Then further optimizations pushed it to $30,000/month. Only at that point — with clear proof of organic traction and a format that converted — did he turn on paid advertising. That's when it jumped to $100,000/month.

The sequencing matters enormously. Paid ads amplify what's already working. If you use them to find product-market fit, you'll burn your budget chasing a signal that doesn't exist yet. Michael used organic content to find the signal first, UGC to scale it cheaply, and paid ads to pour fuel on an already-burning fire.

What the GoTall App Actually Offers

It's worth understanding the product itself, because it's more substantial than just a one-question height calculator.

GoTall includes a Growth Estimator, Nutrition Tracker, Sleep Tracker, Exercise Plans, and Progress Tracking — all oriented around helping teenagers optimize their habits to reach their maximum potential height. It runs on a freemium model, with a yearly subscription at $34.99 and a weekly plan at $5.99. The freemium tier gets users in the door; the subscription is where the revenue lives. Superwall handles the paywall logic.

At roughly 700,000 App Store downloads and 300,000 Android downloads, the user base is real and growing. The combination of a low weekly price point and a clear, emotionally resonant value proposition makes conversion feel natural rather than forced.

The Bigger Lesson

Michael's story dismantles a few myths at once.

First, that you need a groundbreaking original idea. GoTall is a better version of something that already existed on acquire.com. He saw the listing, identified a gap in execution, and built a superior product with better marketing. That's it.

Second, that you need to be deep in tech to build a successful app. Michael came from finance, had hobbyist coding experience, and his real edge was the willingness to post 10 TikToks a day until he found a format that worked.

Third, that niche ideas can't scale. A height prediction app for teenagers sounds like the smallest possible audience. But tap into something tied to esteem and belonging, distribute it through a platform where teenagers already spend hours a day, and suddenly a million downloads doesn't seem that surprising.

He got rejected from every job he wanted and turned it into a $100K/month business before turning 21. If you've been waiting for validation that your "weird little app idea" is worth pursuing — this is it.