This is becoming less and less true as time goes on. It reached a high point during the Bush years but if you look at polling of young people, they are much less patriotic than older people. https://www.the-independent.com/news/world/americas/america-250-anniversary-poll-b2997555.html

Which makes complete sense, since it's very obvious that we aren't the greatest country on earth when a 25 year old with a degree has to struggle just to survive and can't afford rent and going to the hospital bankrupts them.

If you and to just dismiss this as "getting triggered" then go ahead, but that would make it very obvious that you only know this country from TV and the internet and don't actually talk to people from here.

I think it was letterman that started his show with “from New York, the greatest city in the world”

The only people you'll find actually saying that are New Yorkers. And they have said that shit for a LONG ass time. Their arrogant delusions are sort of unmatched when it comes to having the "best"... whatever. Pizza, bagels, art, etc. they'll claim everything they do is the best in the world regardless of reality.

There's American Exceptionalism sure, but in my experience even an unpatriotic New Yorker thinks NY is the best city in the world.

It's actually quite old. At least a century or two, if not more https://en.wikipedia.org/wiki/American_exceptionalism