San Francisco housing is expensive BECAUSE of the incomes. Vancouver housing is expensive DESPITE the incomes. It's more of a housing issue than an income one. If incomes were higher, rents would only go up as well.
The brain drain is slow but inevitable.
I'm willing to bet if you were to map the relative rate of increase of income vs. property values over time that you would see that property values are increasing at a much higher rate than income.
I earn what could be considered a good salary, there's less than zero chance in hell that I could afford property in Marin today short of winning the lottery or massive liquidity event.