Do not expect to make money from a start-up unless you started it. If you did not start it, you are the disposable labour. Sorry.
But, in that first wave, the founders were more likely to be the ones who built the original product. Since then, there's been a dramatic shift from the inventor-run tech company to the financier-run or salesperson-run tech company. In this second generation company, there's considerably less leverage for a non-sales or non-finance employee. I've known a couple people who've gotten rich during the second wave, but none were from the creative team.
Yes, your time is capital. But not when you've already traded it for salary.
Brokers risk their time to try to sell speculative deals. This is why they make a chunk of the deal. No guarantee.
Lawyers get paid by the hour for their time. This is why they can earn a nice living but won't get wildly rich unless they take speculative cases on contingency.