I'm not sure how well looked after Nick Diaz is out of the octagon. It maybe he has people looking after this side of things for him, but I'm pretty sure he hasn't got a clue exactly whats happening with his cash.
For as good a fighter as he is he really is vulnerable in basic life matters like this. The UFC should investigate this on his behalf and appoint financial advisers on his behalf if they believe he is being screwed or just not taking care of his money properly.
I'm not a big Nick Diaz fan, but I'd hate to see him he broke, or ripped off after putting his health on the line.