Why do you assume that the destination city is "even more expensive"? That should only be true half the time (for all pairs of cities, if one is more expensive, then the other must be less expensive).

I think it's more like this: Housing is super overinflated. Either I own or I rent.

If I rent, it may have taken me several local moves to find a situation that is a tolerable combination of price and quality. If I move to a different city, I lose that situation, and I lose all applicable knowledge of how to find another decent one. I have to start over at "low quality and overpriced", and improve my way from there, with several moves along the way. That's a hard psychological pill to swallow.

If I own, moving means paying 6% real estate commission. If housing is extremely expensive, that becomes a big number - though I don't know if that's the critical dynamic in peoples' minds. It may be the same as the renter issue - quality plus a decent price are hard to find.