The Dunning Kruger Effect seems so pleasing a finding that it surely must be true...
If you're incompetent, you can't know you're incompetent ... The skills you need to produce a right answer are exactly the skills you need to recognize what a right answer is....the Hard of Understanding are incompetent to understand that they are incompetent, while the intelligent and learned tend to underestimate their own competence, assuming that many people must be able to understand what they understand.
Most of one's life experience in a nutshell, plus American politics, nearly 97% of Twitter, slebs, "artistic" avant-gardists, &c, explained.
Two unique papers in Numeracy reveal problems with the graphic introduced in the 1999 Kruger and Dunning paper. Subsequent researchers used it, (y − x) versus (x) scatter plots, and related variants for nearly two decades. The authors show how a major part of the body of literature that used these approaches seems to have mistaken and interpreted mathematical artifacts as the products of human behavior.Whether this disproves the DK Effect (a false theory built on the mathematical incompetence of the researchers) or proves it (the researchers being incompetent to understand their errors and ploughing on regardless) I am not sure.