I think they thought of him as the second coming of Jesus himself, and he felt he had to do extraordinary things to live up to that image (which of course is impossible).
I think he secretly hated it and that's why he trashed his own hypocrisy in some interviews, saying that the charity talks were all an act and not true.
And I also think that's a big part of his "I'm stupid / I fucked up" line of defense. Yes, he may think it helps his case (but is he actually that naïve?) But the main goal is to tell his parents "see, the genius you thought I was is actually a complete idiot, what do you make of that?!?"
I think he's happy to suffer if that makes his parents suffer more.
(Of course that's all speculation and pop' psychology and as such isn't worth the electrons it's typed in; but it's a possibility.)