Some will want to stay in proximity to the young people they already know.

The ones that want that already do.

All of them? Your response suggests that.

I’d counter that many young people permanently leave their “hometown” for financial opportunities that are currently only available away from that “hometown”.

For privileged young folks who are “amenity migrants”, your statement would be admittedly true. It might be a bit classist to extend that assumption to all young people.

I'm not convinced that most people will want to move back to their hometown after being away for any non-trivial amount of time. I certainly wouldn't. My old high school friends are different people who I don't know anymore (save for a few who who I'm still close with, who coincidentally also don't live in our hometown and wouldn't move back). My friends are mostly people I've met in my new town, and I wouldn't want to leave them without good reason.

Sure, people who grew up in $COOL_PLACE but moved to $OTHER_PLACE for a job might want to (and be able to) move back to $COOL_PLACE now, but I don't think that generalizes to most of America.

I don’t think it needs to be so absolutely black and white. I just mean, if you lived somewhere for reasons other than “I enjoy living here” you’re likely going to have options that didn’t previously exist.