Both true, he did get a lot carried away with his fortune building. But at the core it was still for his family. Like Carnage said, he never really did explain to his family why he did what he did, that it was (mostly) all for them.
Remember also that he wasn't aware of how much money he had made until Skylar showed him the pile, at which point he stopped, and he didn't even know how much money was there.