> Regarding politics, I wonder if another way to interpret this is people who find San Francisco too liberal (or unsupportive of Trump) and want to move somewhere more representative of how a majority of the country (however you define that) thinks.

I'll provide a personal anecdote...

I lean on the conservative side, and lived in San Francisco for a few years. I never had any particular desire to live somewhere else just to be around others who believe that the nation can be more effectively governed with lower taxes and a leaner bureaucracy; or those who believe that abortion is murder. However, in the last five years, there's been a large uptick in representation of a very opinionated, very loud, and increasingly violent minority of those associated with the left. The kind of people who will call you a Nazi for not agreeing with them, or for suggesting in any context that a person ought to be responsible for their own well-being.

I think I'm not alone in stating that was a factor in my moving away from the area. I did not even vote for Trump in 2016 by the way, and I left in 2017.