If I paid for it, and the studio got a cut of the money I paid for (i.e. I bought it new, not used), then I'm gonna do whatever the fuck I want with it. They got my money, so whether I still have the disc or not isn't any of their damn business.

And I'm certainly not making any profit by selling them - I'm still losing a decent chunk of change (if I get 50% of what I paid for it back, that's way above average), and that money's not being taken away from the studios at all. They still got their percentage from me.

If there's legal ramifications to that, they can charge me or sue me, but they can be damn sure I'll fight it until I win or can't fight anymore.