As far as people’s preferences concerning where they live–I think a lot has to do with family ties. Apart from all of the obviously great reasons for living in San Diego, one of the major factors for us has been staying close to our families.
Both my wife and I are natives, with lots of family here, so that is another reason we’ll probably never leave. I can understand how people who don’t have that situation might prefer living elsewhere.
BG, as you said, it’s true that most people who have a long history in San Diego are pretty much set for life here. Those we’ve known who have had to leave were more recent arrivals.
In recent decades, San Diego has become a much more financially challenging place to live and to retire, and I think that will probably continue to be the case going forward.