The value of real estate in Detroit was tied to the auto industry. When it fell, so did real estate prices. The Bay Area's value does come in large part from the tech industry, but it's also a very important port of entry for trans-Pacific immigration and commerce, and that's a lot less likely to change IMO.

But that's beside the point. Substitute Bay Area with Seattle, Los Angeles, Manhattan, or some other area of your choice. Or, better yet, diversify your portfolio by buying real estate in multiple cities. The same options that are available in the stock investment to tune your risk profile are available in real estate investment as well.

not just Detroit…