I've enjoyed self-effacing musicians such as Sam Hinton in folk and Charlie Byrd in jazz. I've also seen arrogance and volcanic tempers from several folks who shall remain nameless, triggered by on-stage glitches in some cases and pure cantankerousness in others.
However, "I hear tell" is not evidence. I generally wait until I am personally insulted before passing judgement. Truth to say, I have seen more "attitude" from rockers than from folkies or jazz performers.
I almost think some individuals' musical talent, in the extreme, is a bit like the talent of a savant. It develops with few distractions and with total focus. Social skills do not always accompany it.