15% of 0.5% of a billion dollar company is just over $700,000. That's not FU money, but that's a down payment on a 3.5MM home.
Also, I have no way of knowing if the same ownership thing is going to happen again. Giving me another 0.5% of the above calculation. Sure, lots of people make millions in a startup. Way more people make millions, although over a longer time span, in tech companies and index funds.