Earlier quoted context omitted.
80k* %50 = 40k vs. 160k * %35 = 56k Bay area in a nutshell. You can have higher savings rates too, I do around %40 and I could save even more. Working at a startup does make it harder, usually it's better to work at FANG. You also learn a lot and realize the difference between 'facebook does this dev practice because it's huge so it has to vs. it's the better practice'
Pre or post-tax, and at what standard of living? Weather aside, you can get significantly better housing/schools/daycare/whatever for that 80k elsewhere than you can for 160k in the Bay Area. If you're young and single this is probably a non-factor, but for people >30 it can be significant.
If you're starting your own company and want VC investment, I can think of no better place to be than silicon valley, assuming you make use of the social events, meetups, attend YC demo days, rainbow mansion, etc. The personal networking will lead to more and better deals.
But if you have kids, a spouse that doesn't pull in the astronomical salaries, or are trying to bootstrap a company, stay far, far away.