Employees also usually get bonuses, and stock options. Your point is possibly true for companies as big as FAANG ones, but for a startup invested in by YC, it's highly unlikely the founders are getting any real bonuses. They might get some money about in series B or C, but that's already less than 99.9% of startups that get to that stage probably.

You are simplying the situation by thinking about everyone as successful unicorns. Most companies and founders are not.