My take on this movie, Jon's story
At the end of this movie it made me think of how misplaced Jon was. The whole movie kind of is about Jon's voyage, he wanted to be a musician so bad that he could not see that this group he ended up in was really not about sharing music with an audience but rather a way for this odd group to cope with their lives, by sticking together. Like a kind of group therapy. It indeed was a mental hospital,and he had no place in it. Jon realised this in the end, and he managed to repair the damage he had done, and I think he learned that creativity does not need a goal, and it needs no fame.
Also, I think he learned that you don't need to have bad experiences (e.g. a bad childhood) to write music from your heart, you just need to live and not try to be something you are not.
And about the responsibility of influence. It's important in life to listen, and to feel, what is what, otherwise someone end up getting hurt.