On the flip side, some of the best singers on the show clearly lack confidence in their abilities.
A 2009 study1 shows that the most incompetent people actually believe that they are above average.
People that are ignorant that are unskilled or incompetent tend to be very confident of their abilities.
So we believe that we are above average sometimes, whether this is true or not.
Interestingly enough people in the top quartile (i.e. the competent ones) think that they are at a lower level than they really are. They believe that other's are more skilled than they really are and so self-evaluate themselves lower.
If you confident that you are above average at something, what if you are really bad at it?
So even if you are bad at something, you won't figure it out by looking at other people.
The only people who self-evaluate correctly after seeing other people are the competent people, who correctly self-assess that they are better than other people.
If you really want to know if you are above average at something then you must get training from experts.
So be careful before assuming that confidence = competence.
Also, you may want to be careful of any subject which you have not put much effort into but are confident that you are competent.
Odds are there is something that you think that you are good at but it may turn out that you are the idiot!
As Mark Twain once said (ironically, of course):
All you need is ignorance and confidence and the success is sure.