For every 1 person who got a big payout, there are 99 more that just worked themselves to burnout and maybe got a mediocre options payout worth about 1/2 the salary they'd have made at BigCo.
This is probably more true if you're employee number <10 and stick with it through the long haul, which may not be appealing for a variety of reasons. It can also be true if you spin a personal project into a business, but you can do that while employed anywhere.
There isn't any guaranteed, or IMO even likely expectation of a big reward if you join SmallCo and simply "work hard". The reward for that is usually more that higher-ups recognize you're capable and choose you as the go-to person any time they have any sort of tough problem. This is both exhausting and frustrating if you're the designated hero fixer but cannot convince leadership of broader changes they need to make to limit the number of fires that need fighting or train other employees to handle tasks as effectively as you. The general rule that you'll most likely see a salary increase by hopping jobs anyway still applies.