People who make mistaken self-judgments are more likely to overestimate how well they think they are more capable. People who are less likely to make more accurate self- judgements.
Kruger and Dunning (1999) argued that this gross overconfidence occurs because those who lack skill simply are not in a position to accurately recognize the magnitude of their deficits. Their incompetence produces a double curse. First, their lack of skill, by definition, makes it difficult to produce correct responses and, thus, they make many mistakes. Second, this very same lack of skill deprives them of success at the metacognitive task of recognizing when a particular decision is a correct or an incorrect one.
This is true when judging their own responses as well as those of others. The incompetent are not alone in their difficulty with accurate self-assessment. Top performers consistently underestimate how superior or distinctive their performances are relative to their peers.
Auto155
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2702783/