The country you grew up in almost always has a big quality-of-life head start, because it's where your friends and family are.
If you're in a poor country and changing country will get you a 10x increase in salary, that might more than compensate for only seeing your loved ones for a few days every few years. But if you're already pretty well off? Not so much.
The headstart is also in your customs. If you are used living w/o e.g. social security, a migration to the US is far more easy/interesting than when you are used to social security.
If you're in a poor country and changing country will get you a 10x increase in salary, that might more than compensate for only seeing your loved ones for a few days every few years. But if you're already pretty well off? Not so much.