This is very good advice, and there are a number of times in my career (and life, really) that I wish I had respected this mode of thinking. It didn't get through to me until I read it in a book about chess, actually. In the book the author warned that beginners get into trouble by paying attention to momentum. Instead, it suggested, it was better to look at the board each move as freshly as possible and ignore what happened to get it into that state because it was irrelevant.

More often than not, I think that's good advice for darned near everything. I'd say take a fresh look and weigh your options. If you didn't have a job right now is this the one you'd take? If not then stop! Because that's what you're doing every morning, you're taking this job for no better reason than you took it yesterday and the day before that.

This. If the only thing keeping you from bailing is an attachment to past decisions... don't let it keep you.

Exactly. Just because you've spent the last year barely making ends meet, it doesn't mean that you have to spend another year in a similar situation.

Reassess what's important to you and go for it. You need to ensure that your own personal needs are taken care of first before others, and if that means leaving the startup behind, then so be it.