Confidence and Wisdom have a very interesting correlation: Foolish people are often very confident. Above-averagely-wise people are often under-confident. Very wise people are often very confident.
In fact, this is a well known cognitive bias and is known as the Dunning–Kruger effect.
This bias is due to a meta-cognitive inability of low-ability people to recognize their ineptitude and evaluate their ability accurately. On the other hand, high-ability people may underestimate their relative competence because they erroneously assume that tasks which are easy for them are also easy for others!
High-ability individuals often underestimate their relative competence–because they erroneously assume that the tasks which are easy for them are also easy for others!