That is massively, dangerously wrong. Dunning, Kruger and an array of later researchers have shown that while the inept do strongly overestimate their own abilities, the highly able strongly underestimate them. The very able assume that if a task was easy for them it must be easy for everyone, while the completely inept assume that a task seems difficult because it is objectively difficult, and that they must be very able to have made the progress that they did. The lower you estimate your own ability to be, the more likely it is that you are in fact highly able. CF Downing demonstrated that people with high intelligence tend to overestimate the intelligence of people who are similarly intelligent to themselves and underestimate their own. If you think that the people around you are more intelligent than you, you're statistically likely to be the most intelligent person you know.

Personally, I think this is a highly pertinent cognitive bias, so pervasive as to affect nearly every aspect of modern life. I think that our most able thinkers keep quiet for fear of being wrong, whilst the stupidest and least informed in our society shout from the rooftops in blissful ignorance. I think that between the natural effect of "the more you know, the more you realise you don't know" and the pervasive anti-intellectualism in our society, we are becoming dominated by the loud and inept.

In my work as a gambler, I rejoice in this bias, as it is what pays my bills - bad gamblers can't even conceive the idea that there might be skill involved. Unfortunately, I think it is fucking up society - while professional scientists are careful to speak precisely, avoid hyperbole and only make statements that are backed by strong evidence, their opponents feel free to rant and rave, to extrapolate one anecdote into compelling evidence, even to deny the possibility of objectivity.

You mean, everyone is above average? ;)