Americans are hated? I think you hang out in a fairly small social circle if that is the norm. Or are you just one of those self-hating Americans who thinks everyone else is just like you? Guessing that's the case from the use of "y'all"
Maybe you need to travel more? You hear "Americans are hated" by.... Americans mostly. And, I would guess, Americans of a certain political bent that say it more as a badge of their identity rather than it being an honest belief in the truth(literally "America's #1!!!", but for liberals). It's a grade school level understanding of the world(as is "America #1") and I find it a fair indicator of stereotype-oriented thought patterns when I hear it.
By the way, I am not an American and I don't live in the US. So I have a perspective on this which you probably don't have.