I don’t know if you’ve seen the recent news in the US but things are going downhill very quickly. I don’t expect us to stay out of a recession for long once our government collapses into a dictatorship.
Unfortunately you seem to forget that money movements are amoral.
A country could be a brutal dictatorship and still be a great place to grow your wealth. Investors aren’t going to willingly make themselves poorer just because Americans are in a private hell of their own making.
America is still the world’s top consumer. People are broke because they literally consume too much. Debt slaves will make you RICH.
Not really, but diversification often useful; it reduces variance, which is a common goal. And there have been decades (e.g. 2000-2010) where international stocks outperformed American ones.