Housing cost is the #1 reason I moved away, and the #1 reason I stay away.
I lived in Mountain View 2007 to mid-2008 for my job at Google. We were renting a house close to campus at the time and contemplated what it would cost to put down roots and stay -- most likely buying a condo or house. Every time we ran the numbers, it made no sense, so we voted with our feet and moved back to Chicago. I would love to live in the Bay Area again (there's a soft spot in my heart for the running trails of Marin County, in particular), but it still makes no financial sense. The lower cost of living in Chicago adds directly to my personal financial runway and allows me to work on what I want, when I want.
While the cost of living here is brutal, it seems a lot of people are stuck here due to the supply of tech jobs. It would be a lot more risky to live somewhere that does not have such a supply. As someone with a solid software background, if I were to wake up tomorrow and find myself without a job, I'm reasonably sure that after at most a few months of searching I could line at least something up. If that happened in another city, I'd be in panic mode, wondering how many months of living expenses I had left in the bank account and where my family would be moving to next. When you're not in an area with a healthy job market, it's terrifying to be out of a job without severance, and 1 or 2 months away from bankruptcy (ask me how I know this).
I'm not so sure. I think instead the panic might be more acute due to the exhorbitant cost of living. The salary difference is significant, but it's not necessarily enough to confer a rate of savings sufficient for the typical American household (2.5 kids, mortgage, student loan debts, etc.) to withstand more than a few weeks of unemployment, let alone months.
Right now I'm reasonably confident that I can go from being dumped out of my contract to having an equal (or higher) paying contract in a matter of a 2-3 weeks. If (when) that changes, I'll pack my family up and move, probably to Chicago. It's easier and less stressful to save a few months' worth of runway earning $120k in Chicago than it is earning $150k-$180k here. If other personal issues weren't impeding it, I'd already have done so, but circumstances are more likely to keep me here for at least a few years. The hot market here won't last, and it seems to me the hottest parts of the job market now are becoming even more narrowly focused on a segment of the labor market I'm simply not a part of (young, willing to work 50-60 hours a week for no overtime, below-market compensation + an equity lottery ticket and kitschy foosball-table nonsense).
Just as a comparison.. In my city outside the valley I'm confident that with at most a week, I could land a brand new gig that meets my previous rate requirements.
And the same is true for virtually everyone here currently playing the software game.
You are over selling the risk of moving out os the Bay Area. The original commenter mentioned Chicago which is also going through a tech boom with plentiful software jobs to be had.
I'd also add that there is something to be said for diversification of industry. Anecdotally at least, it seems like the last time the tech bubble burst, the bay area was hit the hardest. Other cities had more to fall back on in other industries that need tech (finance, insurance, medical etc). The real advantage to SV is 1) access to VC and 2) it comes back faster after a down cycle.
I lived in Mountain View 2007 to mid-2008 for my job at Google. We were renting a house close to campus at the time and contemplated what it would cost to put down roots and stay -- most likely buying a condo or house. Every time we ran the numbers, it made no sense, so we voted with our feet and moved back to Chicago. I would love to live in the Bay Area again (there's a soft spot in my heart for the running trails of Marin County, in particular), but it still makes no financial sense. The lower cost of living in Chicago adds directly to my personal financial runway and allows me to work on what I want, when I want.