[prostoalex]

1) Facebook or Google already have offices in Seattle, Los Angeles, Austin and other lower-priced locales.

2) The moving scenario works great for single people with no attachments, less so for married people with non-Facebook and non-Google spouses, even less so for such married people living in a school district they like.

3) Even with a single non-attached engineer, how many are company men dreaming about retiring from the same company they work for nowadays? How many are just using Facebook/Google as springboard for their "next step", be it a switch to another large company, fast-growing startup or doing your own startup?

4) If you're not independently wealthy, you want to hedge your bets. Being let go of an engineering job in the Valley is probably less onerous than being laid off from software engineering field in Detroit, as far as job searches, networking, and sacrifices one has to make.