As Paul Graham said on a different thread yesterday, if you have a choice between two explanations and one justifies you being lazy, choose the other one.
I'll agree, "most" is probably way off. It is greater than 0, but it could well be a negligible amount.
By "offer", do you mean for free? Well, duh. What the GP most likely meant is that some people prefer to be homeless rather than having to get and hold down a job to afford a place to live.
Besides the challenge of actually finding a job, a minimum wage job won't cover rent in SF and certainly not with money left over for things like food, transportation or phone service. Have you seen the installation art piece about the minimum wage? It's a box with a crank on it that spits out a penny every 4.97 seconds: http://disinfo.com/2012/12/the-mininum-wage-machine/ That's what working is like to most people, except often more dangerous and demeaning.