Nope. First of all, social mobility in the US is not better than anywhere else (https://www.epi.org/publication/usa-lags-peer-countries-mobi...) . Secondly, it's not that much harder to renounce US citizenship than other countries - in fact, in some ways it's easier because the US is the only country I know of that allows you to renounce citizenship without having another citizenship already. My point was only that you don't have to "actively keep" your citizenship, by visiting the US or any other means.

This is a pleasant fiction, isn’t it? A quick look will tell you that the US is far below the Nordic countries in social mobility. For instance:

https://en.wikipedia.org/wiki/Social_mobility

Also the services that the US Government provides to even their overseas expats is pretty remarkable. I’m not sure there’s another country in the world that can bail you out of a dicey situation within hours in almost any spot on earth.

You don't know what you are talking about. The US overseas generally won't lift a finger unless it has invaded the country in question. Canada, the UK, Germany, Ireland, Japan: all in fact assist.