Sure, there is no guarantee this won't change, but there is no reason to believe you can't vet for founder or team quality at least initially.
And if/when the dynamic changes, quit. It is true that as an employee in a startup you don't usually have much control over how much you make from your options. But you do always have a choice - whether to continue working there or quit.
Yeah, shit happens. But what you want to vet for is what this guy experienced. Ethics, loyalty, temper, commitment, smarts, cooperation, etc. That doesn't guarantee that you won't have a bad experience, but it helps a lot.
If you go into ANY job knowing nothing about your employer/manager/leader other than what you read on their web site and heard about in the interview, you're doing yourself a disservice. Going into a startup like that is like a professional equivalent of a mail order bride.
I've seen really nice people turn into absolute jerks as the success of their company went to their heads.