1. Moving is hard. Even harder for people that have little means. Living in the state you're comfortable isn't going to work for a lot of people.
2. Currently, it doesn't feel like "the state you're comfortable in" will be that way for long in this country.
3. Moving to a country you're comfortable in is the same principle, so why not do that if you're already comfortable moving?
But to play this card,
Also, don't forget that a lot of blue states (if that's where someone wants to live) have been really bad at providing enough housing, so are pretty difficult for someone to move to if they don't have a lot of money.
That's a pipe dream. The division is urban-vs-rural, not state-vs-state. What is now a red state will inexorably become blue as people flock to it. Rinse and repeat.
America has been through divisive times in the past. We'll survive. I think what's notable now is that it's been so damn peaceful for most of our lives that this looks like unprecedented tribalism.