In Musk's case, though, I don't think he's crazy. I just think he's a charismatic con man looking to line his own pockets by selling a pipe dream.
Really? The man was independently wealthy. He could have bought his own island and lived in luxury the rest of his life. Instead he plowed his entire fortune into Tesla and SpaceX and was a couple of weeks away from losing everything. If the 4th SpaceX launch had failed like the previous 3 or if they hadn't figured out the drivetrain problems on the Tesla roadster he would have nothing now.
I'd think it's pretty clear that Musk is motivated by other things than money. You may agree or disagree with his dream, but there's no question the man is sincere.