I'm not sure what your point is. I have a ~$300k/30 mortgage, and I'm not paying less than I would for a 1 bedroom apartment in San Jose.
Even if I could, though, so what? Again: you can live in SV on $19,500/yr. People do it. That doesn't make $19,500 a reasonable comp package.
In discussions like this, people tend to talk as if there are two alternative comp plans: either (a) the package where founders build their own futons out of cinderblocks and shipping pallets, or (c) market salary.
There is, believe it or not, (b): significantly lower than market --- which for a startup founder in SV is probably north of $120k/yr --- and significantly higher than subsistence. The (b) comp plan is the rate that would allow a startup founder to:
(1) Rent (or make mortgage payments on) the same home they had prior to starting the company
(2) Continue making car payments on the car they bought last year
(3) Maintain all previous insurance levels
(4) Maintain phone, cable, and Internet
(5) Cut meals out by 50-75% but keep the grocery list approximately the same
Every one of these items is negotiable, but so is having a private sleeping space. If you want all of them, though, you're paying substantially north of $50k/yr in SV. I'd think $75k is closer to the mark.
The median income in SV is $85k ($96k if you're tech). People judge the quality of their lifestyle based on their peers. It's hard to argue that you'd feel just find with $40k after tax.
I'm getting sucked into what I admit is a very boring discussion, I know. I just wanted to make the (a) (b) (c) point.