I'm not saying America is the center of world intellectualism, but you're also getting quite a selection bias since "stupid American" stories are even popular to other Americans.
As an American, the last 10 years have been a real surprise to me. I've always known that there were incredibly stupid and hateful people, but it seemed like a slowly shrinking minority. The slow, incremental progress of America has led to apathy for most progressive voters. After all, if nothing is broken and it is getting better on its own, why worry about fixing it.
The problem is that a very over the last 100 years, a small but very rich group of psychopaths have been slowly eroding things like our education, journalism, social support, workers rights, judicial systems, and more.
I'm not talking about some secret group like the Illuminati, I'm talking about individual psychopaths like Elon musk who pick one or two things that they feel get in the way of thier ability to grab the power they think they deserve. They whittle away, using their immense wealth to slowly chip at our institutions. And each new one is able to build upon the work of the previous psycho.
The problem is that the last hundred years of slow witling has left us with very weak foundations, and things are beginning to fall apart.
This might be a controversial take, but I don't think racist bigotry is an intelligence thing
The study and measure of intelligence itself is a piece of the rationalization of racism.
We owe a lot of our scientific inheritance to genociders and racists and eugenicists - I wouldn't be quick to assume the MAGA base is just a bunch of dimwitted Americans.
My take? That a third of the american population has taken a liking to fascism.
Fascism isn't borne out of stupidity, it's borne out of greed and desperation. Sure, some of those people are probably as dumb as a bag of rocks (any slice of the american population is liable to have a few), but most are likely just your average-intelligence american who has taken their feelings of fear or envy and rationalized them into fascism.
People like Josef Mangele don't become famous because they're dumb - they become famous because they end up wielding their intelligence against humanity. If we were to assume that everyone with those beliefs is dumb, we'd misunderstand what motivates them and we'd waste our time trying to educate them out of bigotry.