And because they're safe, and because they feel a sense of community with the people they've met there, and because they're able to indulge their hobbies and because they have family that live there and told them it's great, and because...

The reasoning is vast and wild. Job markets are one factor, but there's a huge pile of reasons that factor in. Sometimes that includes being trendy.

Sure, that's why you move from one place with a decent job market to another with a decent job market.

But people an aggregate move towards places that offer economic opportunity and away from those that don't -- hence the waves of migration from rural to urban areas and away from dying cities like Detroit.

The only people (not quite that absolute, but close enough) who move from a place with plentiful opportunity to one without opportunity are those who a) have no choice (or feel they have no choice) -- be it due to being priced out or having to take care of an aging parent; or b) aren't subject to such economic pressures (work remotely or are financially independent).