[Texasian]

This is the same thing everywhere. When I was living in San Antonio, I'd always joke about folks who moved from Austin because they were always saying that "Austin was better X years ago." X being equal to +- 1 year from when they moved to Austin.

[gascan]

Is it not only natural that people move to a city when it is good, and leave when it is not anymore?

I think there's two interpretations of the observation you describe.