I have seen the movie and enjoyed it but I am not at all clear on the myth-making element that you refer to. Sure, the movie necessarily omits several key events in Wilson’s life, aside from the Berry case. I personally would have liked to have learned more about how Landy inveigled his way into Wilson’s life (I have since read that his subsequent detachment was also less abrupt than the film would suggest) but I accept that these are not central to the filmmakers’ intent, which is to dramatise the causes of Wilson’s progressive derangement and later recovery in two distinct phases and to show how his creativity is inextricably bound up with his mental condition. As far as I can tell, in this it is entirely factual. I agree with you that the creative process is explored extremely well in the film but I fail to see the myth-making.