that's why you feel this way. After you lived a life and developed social ties and relationships in place it would be impossible to rebuild those in a radically different country.
Statements like "Retire to Vietnam!" are mostly absurd nonsense - really to go to a place you can't even read the signs?. The most valuable asset one has are the social ties - far easier to live in a boring German village where you know most people than in the most dynamic place on Earth where you never lived before.
the problem is though that this is an idealized version of traditional small towns. My parents are still doing fine, but my grandparents were very isolated at the end of their lives because most peers have died off, are too old or sick to go anywhere, and most young people have left too so it's a very, very insular and lonely environment.
From the stories I read about the state of health, drug abuse and so on in American small towns it appears to be even worse.
Boring life is not necessarily a good thing for older folks. The practical problems of being far away from healthcare and so on aside, I believe being in a young and dynamic environment is a good thing for you if you're old, it keeps people stimulated.
People love painting the image of 'loneliness in the city' vs 'community in the village' but in reality, at least in my experience it's the other way around.
Integrating into a foreign culture is orders of magnitude more difficult - for many perhaps impossible at old age.
In kind of a less extreme situation, I've known several couples who retired in the UK and moved lock stock and barrel to Spain. Even there, I've heard horror stories of getting soul crush homesickness, not being able to sell the house, and eventually returning to the UK and living a very much reduced lifestyle thanks to all the assets being tied up in Spain. It's a massive risk.
The cuisine and the culture in much of the developing world are superb, the cities are dynamic and young, transport and services are cheap, in contrast, going back to my parent's village feels like going to a whale graveyard. Now I'm far from retirement age and maybe I'll mellow out a bit but many western small towns I've seen are outright depressing to live in (and at this point lack basic services and public transport).