The 80th percentile for household income in 2012 was $160,000. This does really crazy things to a relatively static housing supply:
http://www.sfgate.com/bayarea/article/In-growth-of-wealth-ga...
This isn't just about "keeping up with the Joneses." Most families want a) a decent home, and b) a good education for their children. I had to pay an obscene amount for a) in SF, and I was holding my breath while figuring out how to pull off b). My quality of life otherwise was relatively ordinary: I drove a Toyota and didn't go out all that much due to the newborn.
I made a princely sum compared to the average American. Had I lived in average America, I would have lived like a prince (you could literally buy a mansion for the price of my 3BR home in most places in the US). But since I lived in SF, I could only barely afford the basics. This has nothing to do with skewed expectations on quality of life — it's about the skewed economics of the city.