Some might say that someone with so many coins wouldn't destroy the market as they are so invested in it, but what happens if their Buy/Sell cycle doesn't destroy bitcoin in the long run, but they are just taking a wager that they can pull it off enough times while bitcoin is small enough and then quit misbehaving when it's bigger?
Even if you can't regularly do $15 to $8, even 1-2$ in change often enough could eventually give you monopolistic power over the bitcoin system.
For bitcoin's sake- I hope Pirate Returns the money, and the community stays away from such "financial innovation" in the future, even if it's not a ponzi.
It's a feature, not a flaw. If you were rich, would you want us barking at you for being able to "control" our supposedly decentralized perfect new world freedom currency? If it's a problem, it won't be fixed by wishful thinking, sunshine and farts, it will be fixed at the application layer.