Was in Europe this summer. Even if inflation is comparable or worse everything was still far cheaper than the US.
This is a lot easier said than done. Sure you could move to Canada (for example) but better do it before you get over a certain age and you have to demonstrate that you have a certain net worth. If a lot of Americans decide to start leaving that's only going to make it harder to emigrate to other places.
FEIE as an example is a deduction that currently goes for around the first ~$120k you earn, you also have your standard deduction. This only applies if you have spent at least 11 months in another country. Then there's housing, foreign tax credit, and so on.
In reality, most expats who earn any sort of income pay $0 to US. The only requirement is that you file every year, like all citizens to the US. Double dipping, like you're alluding to pretty much does not happen much.
Relinquishing citizenship has a fee of $2350 minimum attached to it, which is hefty, but if you're giving up your citizenship, chances are that the bill is paltry compared to your supposed other benefits.
Getting in’s not easy, not sure how all the obviously-first-gen immigrants working as e.g. taxi drivers in Canada got in. All refugees, maybe? Spouse had a points-granting technical degree and landed a Canadian job in that field before immigrating? They’re secretly famous artists or brain surgeons (special immigration categories) and just moonlighting for fun? Unclear.