They assume that my passion for code or building things (or whatever it may be) should translate directly into work for them. This is especially true of startups. I'm starting to think that I have had more freedom to do what I want in a boring corporate cube farm. I don't want to work for people that want to own my 20 self-improvement hours anymore.
So a startup should be about doing it your way. Working for a startup just means being another cog, doing it someone else's way, except that you are stuck working insane hours for less money.