Real estate prices swing around, wax and wane, just like the stock market does. It's just that there is no real estate price ticker.
Investing in the S&P 500 is even less effort. The last time I bought a house, I had to carefully read and sign about 50 pages of legal papers. Buying stocks is just pushing a button.
In places like the Bay Area, property values pretty much never go down in price, and the YoY relative increase is on par with that of index funds. Combine that with rental income, and you can very likely beat an index fund. Mortgages offer much more leverage than margin loans, which helps offset the upfront capital cost.
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.
Investing in the S&P 500 is even less effort. The last time I bought a house, I had to carefully read and sign about 50 pages of legal papers. Buying stocks is just pushing a button.