1) Immigration. 60 million foreign born people moved to the us in the last 30 years, plus another 20mil illegals. This was possible due to their policies, decisions and inactions. Today they have a massive problem they created.
2)China. The US built China up by investing starting in 1979, then supporting WTO membership. Today China is a peer competitor, US is repositioning to counter China which they through their policies strengthened and enabled them to become powerful as they are today. Created their own problem which may turn out to be existential.
3) Iraq, still noone knows why they invaded (we know bc of israel), but it opened the flood gates to destabilization, isis, Iranian influence whom they are today fighting a hybrid war against, lost trillions, thousands of lives, tens of thousands injured. Noone was held accountable, shows the corruption. Again entered with no clear plan.
4) Afghanistan, military loss, changed nothing only spent trillion bucks and lives. No clear plan or exit strategy.
5) 2008 financial crisis, own making due to bad laws, corruption in government (they call it lobbying), etc. US after that never recovered and the printing machine went crazy.
This is just some recent short sighted stuff. You see, every schmuck in us government wants to make a name of themselves, start an agency, or something, do a war, stop a war, do this do that … all for self gain without national strategy considered. This is why you have 50 intel agencies, mainly bc every schmuck wanted to create their own, get a budget and leave a legacy, not actually for the good of the country. If anything this bureaucracy creates confusion.
So on and so on. This is why the us cannot be taken seriously, they are like a teenager with an unlimited credit card. They are even destroying their alliances they created after ww2.