You're scary and dangerous to bigger companies. They know you know how to leave and survive at any time, and expect you to get tired of the crazy schedules, overtime, and all that at any time. (At least I've known managers who thought that about your type).
Probably why I'm so startup oriented. Of my fulltime jobs most are startups. Just prefer if i'm going to commit then I'd rather comit to a company I can have the greatest impact at and where the risks/rewards are highest. I'm 'built' for startups, just how my psyche works.
Sadly, my experience is that they're scary to a lot of startups as well. Startups often have one or two former big company types working for them, which may be all that's needed to tip the scales against you.