If you want people to stay, give them a decent financial incentive.
I keep seeing this sentiment, but I think it's important to distinguish between "don't give your people worthless equity instead of a good salary" and "I'm just here for the money." Starting to see a lot of the latter around here and it's disheartening. Sure, broken dreams and failed visions and all of that happens, but it's part of the process when you try to do "big" things. Widespread cynicism will kill high-tech.