I think every economic migrant I've ever met (myself included) talks about moving home realtively soon "I'm only here for 2/5/ < 10 years", but very few of us do because we become established, make new friends, acquire lots of possessions. Some DO move home for major life events like kids arriving (or leaving) but I don't think it's as many as you assume, it's just very notable.

I'm lucky enough to have two sets of family still back home, close enough to visit easily but far enough to make it meaningful and intentional. The desire to move back has weakened every year.