The current tech bubble has some fundamental differences to the last one. Specifically, while some of the pain will hit public markets the vast majority of people left holding bags of burning crap this time around are the VC firms and other private investors. The SF Bay region is going to have an implosion but the impact on the broader stock market and US economy will be quite limited.

In short, if you just bought a big chunk of San Francisco real estate on the basis that you pay it off in a few years when you cash out the options in your hyped up tech startup... well good luck with that.