I think what makes San Francisco a target is that it isn't a great place for those without children who would be classified as wealthy in any other part of the country.
You can probably find a path to home ownership in a safe neighborhood with decent services in any city in the country if you are in the upper quartile of incomes for that area.
The housing prices in San Francisco are such that most incomes even in the upper quartile would take a decade to save for a downpayment. You need two incomes (Two working parents) in the upper quartile of incomes in the area to get you to home ownership in a good neighborhood.