Not really. If he pays people back X bitcoins, he has X bitcoins fewer than if he doesn't pay people back. That's true regardless of how he acquired those bitcoins. If he can get away with not paying people back, his incentive not to pay them back is the same. (Of course, if he doesn't have the bitcoins, paying people back is not an option.)

The point I'm trying to make is that even if you don't think Pirate was running a ponzi scheme and think we actually made huge profits, it doesn't follow that he'll make the promised payouts. He could still default, and for basically the same reason.