It seems to me that what you describe is not limited to musicians. There are people in all walks of life and at all levels of ability or training who are:
humble
snobs
keen
depressed
depressing
dismissive
complimentary
excitable
exciting
teachers (real onws, not "wannabes")
perpetual students
innovativors
emulators
disinterested
extroverted
introverted
self centred
encouraging
etc..

However it does seem that the arts often attracts people from the extremes of most character types.

--=-- My credo: If it's worth doing, it's worth overdoing - just ask my missus, she'll tell ya laugh --=--
You're only paranoid if you're wrong!