So why is this? And why should we be forgiving? One reason is that we owe a great deal to great artists and it costs us nothing to be grateful. Another is that it is rather more gracious to be forgiving to the dead. But we are still left with the why. In order to answer that, I think we have to put ourselves in their shoes.
A lot of very, very talented people somehow never manage to achieve success and the reason why begins to answer the question: they are too nice. If you are very talented at something, the greatest opposition you will face is not, as with most of us, your own incompetence. No, indeed, the greatest resistance will come from your friends, neighbors and associates who will resent, sometimes bitterly, that you are more talented than they are. Most people can be pretty mean about this. Children are particularly adept at picking out those who do not fit well in the herd and punishing them unmercifully. One suspects that the arrogance and narcissism and dysfunction of great artists forms pretty quickly--as soon as they encounter their less-talented peers! You either give in and try and fit in, which means concealing if not actually suppressing your abilities, or you fight back and try to give them as good as you are getting. This means learning how to be a nasty piece of work yourself!
Going back to my friend, who provided me with some insight. He was a brilliant, truly brilliant, musician. But when I met him in first year university he was not, as one would expect, enrolled in the music department. No, he did a degree in psychology instead. After meeting the theory professor I started to see why. This fellow, a perfectly decent mediocrity, probably knew half as much about music theory as did my friend James. I recall one conversation with him in which he explained at length the difference between conical and parallel recorder bores in the Renaissance and Baroque. This guy is going to sit in first year theory and have someone explain that 7ths resolve down? I don't think so!
Nasty bullying is one thing, but as your young talented genius grows older he will encounter something even worse: mediocrity. At least with bullies you recognize that they are the enemy and you fight back. But what about the host of well-meaning mediocrities that staff most music schools and are the arts administrators hiring and firing and giving out grants and commissions? They are the ones that are going to make or break your career. And most of the time, if you really are a brilliant artist, you are going to make them uncomfortable with their mediocrity and they will simply sidetrack you every chance they get.
A truly talented artist often has the choice between marinating in bitterness or fighting back. How do you fight mediocrity? As we see from the careers of many artists, it is with boldness and arrogance--but a special kind of arrogance that comes out whenever you encounter a mediocrity trying to tell you what to do. Now doesn't that explain a lot of seemingly dysfunctional behavior? Some artists learn to deal with people by being, well, a bit outrageous, most of the time. And it often seems to work.
Let's listen to one genuine genius who had to fight the particularly strong and determined mediocrity that dominates Canadian cultural life: Glenn Gould. Here he is playing the Brahms Piano Concerto No. 1 conducted by Leonard Bernstein. Bernstein was so uncomfortable with Gould's interpretation that he felt he had to deliver a speech before, separating himself from the interpretation!
(No, Bernstein was not Canadian, nor was he a mediocrity. Still, this was the most salient example I could find in YouTube of genius struggling to be heard.)