OK, let's be honest, Sturgeons' Law (or Revelation) states that '90% of everything is crap'. Now it is observable that some 90% of humanity, of every race, gender, sexuality and creed, can be handily described by the phrases 'dim as a Toc-H lamp' or 'as thick as two short planks'.
I myself, be it noted, am a Bear of Very Little Brain, so I should know!
That said, the degree of gross stupidity, childishness and lack of either discipline or moral fibre evident in Trump and his followers goes above and beyond. 74 million of them voted for Trump, again, in the teeth of four years of unmitigated disaster. That is stupidity on a truly epic scale.
Maybe it's something in the water?