If you're on your first VC-funded startup, you'll probably get torn up by liquidation preferences and dilution for executive hires (that you had no say in; they were VC injections) and various other things, and not get very rich. You could end up worse off than an employee (because they get to take real salaries; you're hosed if your equity gets zeroed). You'll have to play a second time (capitalizing on your reputation, having joined Those Who Have Completed An Exit) to get what you came to the game for. It's like the record industry: you make money on your second album, because the record company has leverage to screw you on the first one.
If you're a manager or executive-level hire, you're probably never going to get the investor contact you were promised and, if you do, you probably won't be allowed to say much, so the networking you were promised won't happen.
If you're an engineer, you're probably not going to get the "leadership" (executive) position you were promised. It'll be given to some external asshat when the company goes in to "scaling"/social-climbing mode and starts hiring "real X's" (i.e. not the fools who worked for 90 hours per week and 50% of market salaries, judged not to be good enough for prime time).
Only a tiny percentage of VC-funded startups have a real engineering culture (pre-apocalyptic Google) where you can do well as an engineer without becoming a manager. If that's what you want, your odds are better (not great, but better) at a place like Google.
Most VC-funded startups grow too fast to keep a decent culture, and the executive positions often get handed out by VC to their underachieving friends who couldn't make it on their own.
