Confidence is a currency that relies upon accepted standards to gain its value. These standards are personal, cultural, historical. As you feel confident or lack confidence, you're comparing yourself to someone or something. This can be a deal breaker for musicians, many of whom revere artistic heroes, predecessors, or ideals that may never be outdone. So why? And then what? It takes a certain quality of character to play a game you know you're not going to win. Unless you don't care about winning. 

We discover our heroes and set their accomplishments as pillars against which we can measure our own. "She writes better music (than I do). He packs more emotion into a vocal (than me)." That sort of thing. Your heroes and my heroes may or may not be the same but that does not matter relative to this process of confidence & comparison. The greats have done greater. 

Get back to ground level. You're working with sounds in a room for a moment. For a lifetime.