"Ninety-four percent of college professors believe they are above average teachers, and 90 percent of drivers believe they are above average behind the wheel. Researchers Paul J.H. Schoemaker and J. Edward Russo gave computer executives quizzes on their industry. Afterward, the executives estimated that they had gotten 5 percent of the answers wrong. In fact, they had gotten 80 percent of the answers wrong" David Brooks, NYT
It seems that the old saying "to thine own self be true" has undergone a hyper-transformation.
Maybe it's good to simply ask oneself, occasionally, 'what if everything I believed was wrong and the opposite was true".
Often it is only when we meet the opposite of something that we can really define the something…