I used to have panic attacks on stage. I would be in full panic attack mode in a full room of people thinking to myself "when will this be over??"......I lost gigs because it was effecting my playing. This is with many hundreds of gigs under my belt. I felt completely inadequate. I was self taught, basically playing by ear for many years. Learning more about music helped a great deal. Learning to not hate myself with every "wrong" note helped even more. Being in NY for 2 1/2 years was the best thing that I ever did for myself, because I realized that so many of my heroes also struggled with self worth and being "good enough". I still get nervous, and it can still effect my playing, but at my best, when the voices aren't there and all I'm doing is reacting to what is happening around me, I am elated...and I get to experience something that feels like real life magic in a very complicated world.
I can see why so many musicians find their thing and stick to that. It's comfortable. When you do something that involves improvisation heavily, you're taking a chance every time. I've seen some heroes crash and burn in front of an audience, and I respect them even more, because they took a chance, and because they'll get back up and do it again.