Little known fact: Crispin Glover refused to be in Back to the Future 2. So director Robert Zemeckis hired a doppelgänger, put him in makeup, and used old clips from Glover's past work on set to fill in any holes. Needless to say, that pissed off the actor (who sued). And now, many years later Glover is elaborating on why he refused to return to the BTTF2 set.
When Glover appeared on the Opie and Anthony Show, he revealed that he was upset with the materialistic happy ending of the first film. He didn't like that the McFlys were happier people because they were more prosperous financially. And he felt the idea that money = happiness is BS.
Sure, okay, why not? Although it's kind of odd that Glover is now claiming he left the BTTF series to protest against materialism, when he's previously claimed he ditched the movies because they wouldn't pay him enough.