On one hand, you have people earning six figures fighting for the dwindling, ever inflated supply of conventional housing options, and on the other, you have people like Nadia Eghbal who display the utmost resourcefulness and manage to live in SF for $20k a year (http://helloimnadia.com/post/52242701025/how-to-live-in-san-...). Really goes back to what pg says about being relentlessly resourceful.
In the end, if you really want to get settled in SF, all it takes is some persistence and a healthy network. (I moved here when I knew next to no one and managed to find home at a coliving space called Startuphouse for most of last year; not only was my stay free but it gave me a fantastic network on which to jumpstart life here.)