Because your country's ego has run amock. You blind yourselves. You kill yourselves.
The world turns its back on you not because it doesn't care. But there is nothing else it can do to try and convince your people not to destroy themselves...
But when you shoot up high schools, vote in people like Trump, and allow cancer patients to go bankrupt... what else can we do but watch and pity?...
That's all I can say really... discussion is over... I think that is a lot of people's stance. Why try to save or even interact with a country that is so bent on self destruction?
The world will move on... You will not.
It's that simple... I mean we will start to see it quite literally when America is still using coal and gas while every other country has moved to electric vehicles. It is one of many changes that will break out of discussion and into a place where people can feel the effects of their failings.