I don't think expatriats/retirees leave America to live in overpopulated cities abroad. If anything, they move to the rural/small towns where they buy a plot of land to build their house, and live off agriculture and cattle, pork, chicken, fishing, whatever.
Seems even more ideal now with the wide spread use of solar panels, water filters, cell phone antennas that you can put on the roof of your house, 4g usb modems that you can attach to your laptop, etc.
If you retired to another country, that would be the way to go, I think. If you move to a big city, you couldn't live off the land, so it would be the same thing as staying where you were before you tired or expatriated.
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you think any of these coli millionaires know the first thing about working some land
The couple of times I have met Americans living abroad they live in a large city running a small successful business and tend to fly back here at least three to four times a year