It’s true, for people earning tech level salaries, the Bay Area is actually ‘affordable’ - see a comparison of earning and cost of living between SF and Kansas City here: https://ramenretirement.com/2018/05/14/cost-of-living/

You’ll save a higher percent and absolute amount of money working in the bay.

Of course, the issue is that not everyone earns $300K+ per year. Unless you make it into a senior role at a tech company by the time you want to have kids, living a ‘normal’ life in the Bay will be hard. Even doctors and dentists will struggle. I completely understand why people would want to leave. I expect they will. The Bay Area is great, but America is an amazing, beautiful place, and fine food / coffee / culture has spread far beyond the streets of SF these days.