For a lot of people who want to become a chair, moving is the only option. Timing, internal politics, etc. can make it difficult to move up into a position at the place you’ve built your career. It’s definitely more unusual to move once you’re chair, particularly for a position that I think most would agree is lateral, at best. Money? Maybe. California is expensive, but if you’ve been in California for years, chances are you’ve bought your home and gotten used to the cost of living. Could it be SO much more money that any reasonable person would jump ship? Sure, why not. Opportunity to build something/leave a legacy? That’s certainly a powerful motivator for the types of people who become chairs.