So you should always stay on top of people's vesting schedules.
The thing that kills startups at some level, is the founders giving up.
The track record for founders that don't already know each other is really bad.
Many of the best YC companies have had phenomenally small number of employees for their first year, sometimes none besides the founders.
You have to find a small market in which you can get a monopoly and then quickly expand.
... but the pendulum has swung way out of whack here. A bad idea is still bad, and the pivot happy world we're in today feels suboptimal.