The dunning kreuger effect is useless. Dumb people think they are smart, smart people think they are smart. Nothing to be gleaned from that. Only at the very fringe of the intelligent side do the lines of actual intelligence and perceived intelligence cross.
Actually the tendency is, that the more you know the more aware you get of the things you don't know. So while dumb people may overestimate their aptitude the smarter people tend to underestimate themselves. The most extreme manifestation would probably be the impostor syndrome. https://en.wikipedia.org/wiki/Impostor_syndrome
What I take from Dunning-Kruger is that unskilled people have misconceptions about themselves, not being aware of what they don't know. Likewise, skilled people have misconceptions about others, assuming they know as much as they do.
Its very easy to forget all the efforts invested in learning a skill when you've been using that skill for many years. When it becomes second nature, you assume its also that way for others.
I have and it's very insightful. The people in the studies that were least competent were also, relatively, the most delusional of their inadequacies. This principle explains why you get people with little coding experience applying to developer jobs and failing the simply FizzBuzz exercise.
