I used to like gigging with a rock band in my teens and early twenties, and I've done one or two solo gigs since then. It wasn't really the performing part I liked in the band, it was just the energy and stuff of the music when I got to play with other musicians like that. The solo gig... it was easy money, but I had to forget the audience was there to start with, made me too nervous, but after a while I warmed up and started interacting with them.
I will never ever pick up a guitar or start playing/singing in front of people, unless I've been specifically booked to do it, or unless I can be sure nobody's really noticing. the minute people start requesting things, if I'm just playing to myself informally, or the minute I notice that anyone's watching or listening, I clam up.
This is all basically because I think I suck, regardless of what anyone else says.