This poll isn't very useful. Given that you can't even get a cheap apartment for much less than $2,000 per month in SF I don't see how anyone could live on less than 36k per year in the bay area before taxes. There has to be more to these numbers perhaps they have a large stash of personal savings they are living off or a significant other with a good paying job.
I'm not a founder, but I spent something around 30k last year while living in SF. I have a roommate, don't eat out very often and take advantage of work food options, take transit/walk almost everywhere, and don't purchase much stuff. Unsure of the tax burden at those rates, but I think you'd have over 30k.
