The World Loves Dysfunctional Confidence
Generally it is considered a sign of weakness to appear unsure. There is a prevailing censure against uncertainty and those who acknowledge their ignorance may expect to be replaced by more confident competitors. [While] an unbiased appreciation of uncertainty is a cornerstone of rationality, this is not what people want. Acting on pretended knowledge is often the preferred solution.
Taken from the book Thinking, Fast And Slow by Daniel Kahneman