A lot of that negativity can be traced back to Adolph Rupp.
I chalk up a lot of the problems with American crowds is we as a whole have become addicted to our entertainment options because they are so plentiful in options, they are largely readily available, and they are also largely easily accessible. Like AEW, WWE, and the sports leagues aren't just competing amongst themselves for entertainment, it's an endless amount of things due to the internet, social media, tv, video games, music, etc. and all that stuff is available straight from your phone no matter where you are.
You find something you really like or love, so you start exposing yourself to it frequently to chase that dopamine high because all you got to do to get it is pick up that smart phone. The more you expose yourself to it, the more you desensitize yourself to it.
You've seen so much and have access to so much of it that the only time it pops you is when it comes close to replicating that first hit, even if other experiences are objectively good they do nothing for you because they aren't how like it used to be, even if it might objectively be just as good as it used to be or even better.
But you keep soldiering on, looking for that next high, reminiscing about the good ole days, trying to recreate that first experience you'll never be able to replicate again without taking a healthy break or moving on to your next fix to fill the void.