Detroit is a ghost town, but the suburbs are fine. The story of Detroit is one of urban decay. Detroit's population has declined, but the metro area's population has been steadily growing. Detroit's downtown is not seeing a resurgence because there basically isn't one. It's a ton of 1950's low density housing stock.
And that housing stock overseen by a corrupt government that embezzled from the public, and a school board presided by a guy who seemingly can't write. It's a city whose politics are scarred by _multiple_ race riots.
In contrast, SV is a network of small suburban towns, all of which are happily constructing new office spaces but virtually no new housing. Rent prices are 3k USD a month, highest in the nation. An economic downturn shifts the local market from 'absurdly unaffordable' to 'merely very expensive'. And due to California's own political schemes, a permanent drop in housing prices would probably help local governments balance the books if it meant they could pay folks less while still taking in the same amount of tax revenues due to Prop 13.