If you're an employee hoping to make it rich by working on someone else's startup you're doing it wrong. Work for someone else because you need steady pay. Work for someone else because you appreciate what they're doing.
If you want to make a lot of money you need to take risks. Start your own startup. Go 4+ years without a salary. The co founders might not be the ones actually building the product but they're the ones taking the risk. They're the ones not sleeping at night. Trust me. It's a far better gig to just get paid as an employee than spend years on a startup that eventually fails. If Silicon Valley has done anything it's give young people the false impression that starting a startup is a way to get rich.
Well...it is. In the same way that playing the lottery is a way to get rich. One is much easier than the other.