The left are simply contrarians and cynics, they have to go against the grain and be against whatever is the norm in order to feel special and to stroke their own egos.
America is a country where the primary population happens to be white, it's the norm, therefore it's bad, if this was some alternate universe where the majority of the population was Native American we'd be hearing about "red privilege" and the plight of the poor oppressed class of Europeans who just want to come here to make a better life for themselves.
It scares the living shit out of some people to think of living in a country of hundreds of millions on a planet of billions of people, it makes you seem insignificant, therefore they have a desire to stand out from the crowd any way they can and the simplest way to do that is to be discontent, to complain about things most other people don't.
Whatever you'd put in front of a leftist, no matter what it is, no matter how good it is, they would poke holes in it, they would be unhappy, they would have a desire to subvert and destroy it just so they can have something to do with their lives.
A real wake up call for me was when I read the prologue to Michael Moore's book "Stupid White Men" from 2000, in which Moore goes on and on about how terrible life is for the average person in America in the year 2000, a year that now seems like downright a paradise compared to 2020 and that was when I realized that you could plop that fatass in any year of American history and he would see life as terrible, he would never be happy, that's what Moore and the people that think like him are like.
