Viktor and Patrik, any relationship?

Yes, we're brothers.

9% feels like an insanely high probability for any given 19yo to become a millionaire on their own merits within a year.

OP is likelier than most because they made this market and build indie apps. But yeah 9% or 5% is still way too high.

Because of the potential ambiguity, consider using international thousands separators (spaces), instead of the German period (.), as English-speaking countries use a comma (,) as their thousands separator

I edited it, thanks for your suggestion.

does it need to be $1,000,000 in currency, or total net worth, and how would net worth be calculated. Like if you build a business and got a credible offer for stake that values your business at $1 million, would that be a YES?

yes, it would be YES. i edited the description to total net worth. In case of any speculations, I would have to provide evidence by a reliable third party (financial advisor certification etc.).

Would shenanigans like Unlimited Money Ltd count, where you make a company initialised with a vast amount of shares and sell one share to someone in the street for barely enough that technically the whole company is worth millions?

No, they wouldn't count. (lol)