Not no taxes, just something that maintains a good reward/risk balance and an invcentive for people to be founders or early employees of these types of companies. The UK used to have so-called Entrepreneur's Relief, for example. Some countries have low capital gains tax regimes. It's not an uncommon thing.

(Sure, a country could gleefully milk everyone to the max, but then they can't complain when they lack for entrepreneurship.)

It just makes no sense and has never been necessary to incentivize Americans to take business risk. I don't understand why the entrepreneur, who is presumably getting a big exit in this scenario, deserves additional tax relief on top of that windfall. That sounds like another way for the rich to get even richer.