When you add up how much a life costs in SF compared to many other places (and in my case I was comparing to life in a large West-European city where I currently live, and where driving/owning a car is a rarity, where healthcare is ubiquitous and relatively inexpensive), there is a significant economic advantage when earning nearly half what you'd earn in SF.

I'm not just talking about rent (which, incidentally, for my family, 2K per month is much lower than the rent we were looking at to accommodate our kids and private life without roommates in SF), but also about how much you spend on your transportation or gas every day, your healthcare premiums and deductibles, cost of groceries and entertainment, auto mortgages and/or insurance for 2 cars (because 1 car for a family wouldn't cut it there).... and the answer becomes obvious.