To add a counter-anecdote, I left a startup while still having a good amount of faith in the company. Left after finishing work on a couple of their products because I wanted a lifestyle change and had an opportunity to strike out on my own venture. The product was great, but engineering culture was a death march, partially due to the seasonal industry (hardware/toys) and partially due to management.
Oddly enough, a bunch of other engineers also left shortly after -- after all the hard work was done. Company is profitable now due to increased sales, but also cutting salary costs. Strike price was still low when I left, so I bought my options.
Just playing devil's advocate here: So they are leaving because they have low faith in the company, but still expect to be able to collect rewards on other peoples' work years later if the company happens to succeed?
If they didn't have a high degree of confidence in the company, the safe bet would always be to not exercise.
This mentality is dangerous and pernicious. We have vesting schedules for a reason. They'd be reaping the rewards of their past work, not other people's future work.
