Many people have deep ties to a place — as caregivers to aging parents, as members of diaspora enclaves, or as young people willing to struggle through a few years of hardship for the chance of success. Many others have seen the writing on the wall and moved elsewhere, and more power to them. It's a question of whether individual solutions (people can just move somewhere else) compose into societal solutions (we need lots of "unskilled" labor or our cities will collapse into chaos within days).