Exactly @greenpea  a lot of great artists aren't confident of their ability, and of those who appear confident it's often a type of bluff. 

In music we're taught if you make a mistake while playing don't say sorry, or go back over it, just keep going, your audience is there to have a lovely time, not a note perfect time.  So we get used to making mistakes and not saying sorry.

Unfortunately some people then carry that into life when they hurt others, even deliberately, and most of them aren't musicians or performing artists, they just don't like examining themselves.

In music the principle is it must be a beautiful experience, not a perfect one.  Whatever music you like, if it gives you a wonderful and meaningful experience it's great music, whether it's "The Wheels on the Bus" or Vaughan-Williams' "Scream from the Apocalypse".