Sometimes I feel like people who sign onto startups in SV as employees are sort of like DC people who sign onto different candidates' campaigns. Every not-yet-mature/proven startup is, in a way, a kind of campaign.
What's not mentioned is many companies these days have loyalty toward their employees. Why should you be loyal and dedicate your whole life to something that's not loyal to you?
Companies are increasingly hiring people as contract workers. Which I think is more honest because it doesn't give the illusion that you'll be taken care. Not that we're ever entitled to such privilege.
It's a dog eats dog world. Working at one company for decades can make it much harder to find another job if you're let go.