"The Dunning–Kruger effect is a cognitive bias wherein persons of low ability suffer from illusory superiority, mistakenly assessing their ability as greater than it is. The cognitive bias of illusory superiority derives from the metacognitive inability of low-ability people to recognize their ineptitude, without which they cannot accurately evaluate their actual competence."
Or in other words, very, very stupid people don't realize how stupid they really are, and in fact, they believe they are superior to the next guy. The stupid people are so stupid, they are incapable of figuring out their own deep, abiding stupidity.
Remind you of anyone? Or anyone's followers? It's one thing to know of a theory, it's another to see it in practice, daily, on the big and little screens everywhere.
Also: "As described by David Dunning and Justin Kruger, the cognitive bias of illusory superiority results from an internal illusion in people of low ability and from external misperception in people of high ability: "The miscalibration of the incompetent stems from an error about the self, whereas the miscalibration of the highly competent stems from an error about others." Hence the analogous corollary to the Dunning–Kruger effect indicates that persons of high-ability underestimate their relative competence, erroneously presuming that tasks that are easy for them to perform are easy for other people too."
So it's not just about stupid people either. The really stupid "incompetent" people misunderstand their own stupidity. And the not so stupid, sort of competent people misunderstand the stupidity of others. So people who are competent tend to overestimate the competence of the stupid ones.
That explains all those frustrating conversations you've been having with our President's supporters. It's all pretty much a Stupid-Fest!
"My brain hurts!"