I'd say close to one-third of the 360 games I bought were from the resale market (but only 1 was used. Rest was brand new sealed stuff that other gamers bought but never got around to playing. So they sold on ebay and what not). And I've mainly switched to renting now (subscription). There's nothing illegal or morally wrong with buying second-hand or renting. It's good for my wallet, that's why I do it. Capitalism isn't about charity. As a consumer, I'm going to go with what I see to be a good deal. And if gaming companies go out of business because of that, then maybe they need to scale down their budgets for financially unsuccessful games so that they don't lose so much money.
If for eg. people don't want to pay full price for a short single-player game or say a light gun shooter (ie. Dead Space Extraction, the recent RE game), what should companies do? Bitch and complain? No. How about scale down the production costs of these games so that they can be profitable. Gaming companies have to realize that you can't extract blood from a stone. Gamers aren't exactly loaded with cash. Especially during these tough economic times. They should scale-down production of games with low demand accordingly to stay in the black. I'm not saying to scale-down production for games across the board. Highly successful games like Assassin's Creed should stay big budget. But if you have short singleplayer HD games with big budgets but low purchasing demand and rail shooters with low demand at $50, your production budget should scale down accordingly.