As someone who just moved from Portland OR to the Bay Area in order to take a "corporate" engineering job in SF (and got a >40% raise in the process) I can say with confidence that the cost of living here, even outside the city (specifically Berkeley for me) is easily 2.5x what is was back in PDX, even with a 60 minute commute and meals comped at the office.
It's not just housing (which costs easily 2x what it does in or near any 2nd-tier tech city) - transportation, food, and mundane but pleasant things like pints of microbrew and movie tickets are way more expensive, too.
Cost of living 2.5x??? Berkeley is not, iirc, exactly the nexus of affordable living. I don't know; maybe I just have cheaper tastes? I agree that rents can be MUCH more expensive; I'd probably pay between 1200 and 1500 for the apartment I live in now (2-2.5x what I currently pay). But I just never felt like it was that dramatic for me.
It's not just housing (which costs easily 2x what it does in or near any 2nd-tier tech city) - transportation, food, and mundane but pleasant things like pints of microbrew and movie tickets are way more expensive, too.