Lots O reasons.
Space, finances, POS game, need it to make monies, etc etc

I think that's what I'm answering.

I have only so much space, I get a game and it's a total piece of shit, lets call it; "Ghostbusters." So I sell it that makes sense.
I had JP and it wasn't grabbing me, it was a cool game but not for me. Well, I sold it becasue I need the space and I need it's monies to buy another new game.
I don't have a big disposable income, but since everyone is a lawyer now I'm probably in the minority. Lot's people here can afford to buy a machine and play it for a week and sell it and take a $400 lose, price of doing business.

Now, the real question is why someone buys a machine, installs $600 worth of mods and then sells it in a week.

All kinds man, all kinds.

That's on top of the obvious "people are horrible with monies" and buy tons of shit they cant afford.

Haha Original receipt!