I think here are two things in play: First the other end of the Dunning Kruger effect where competent people underestimate their competence rank. Second, only

I think here are two things in play: First the other end of the Dunning Kruger effect where competent people underestimate their competence rank. Second, only good mathematicians[1] can recognize the massive gap between good mathematician and a real top class mathematical genius. For the mere mortals they both are so far that they look alike. [1] Mathematician can be replaced with any other talent/competence. Actually I realized this phenomena first in sports. The world's ultimate top and a very good amateur look perfectly as good to a complete beginner. But when you get to the very good amateur level, you start to realize the massive amount of work (and maybe talent) that makes the difference between you and the ultimate top.