I used to sell some games back in the day mainly games I didn't really enjoy much but ever since those few years back I've stopped selling them and instead kept them usually just to go back to them and play them
Depends on the game... I keep the ones that I really like and will want to play again someday. And I get rid of the ones that I feel have absolutely no re-play value or that suck in general (I did not like).
It would be stupid of me to keep games I don't want to play ever again....and to get rid of games that I will want to play again some day.