I can't really sell Xbox games cause most of them are worth less than $10.
Just because something isn't worth a lot doesn't mean you can't sell it. Even if you sell 50 games in a lot for $100, it is still something. You have more space, you have less stuff, you have some money that you didn't have before. If this sounds good to you, it's really easy to sign up. And if you do feel like replaying any of those games in the future, it's likely that you'll be able to easily re-acquire them.
I don't get people that hold on to the past like that, especially with games. Old games just feel so clunky and often look terrible today. Why go back and play a game I've already beat when there's thousands of new things I could play instead, a not insignificant number of which are emulating those old games but with crisp, widescreen HD resolution graphics and more modern mechanics, but otherwise evoke the same type of feeling as the old ones (Shovel Knight for example)?
This is like asking
"Why go back to that old pizza place in your old neighborhood? There are lots of places with good pizza."
Or
"Why go back to that old playground you grew up with?"
With all 3 of those questions the answer is the same. Because it's THAT SPECIFIC one. I don't want any old pizza place, I want that favorite one from my hometown that gives me the taste I grew up with, unchanged all these years later. Because it's THAT playground, where all those things happened with my friends. Or, because it's Bob-Omb Battlefield.
Movies and video games are in a unique position, in this regard. Playgrounds can be paved over or re-zoned. Pizza places can close. Homes can disappear. But video games and movies, 10, 20, 30 or more years later, are exactly the same. You can relive that experience at any time, now and forever, and it will be 100% identical to what it was years ago, with no exceptions, for better or worse. And while some folks won't care to relive those experiences, I, personally, from time to time, will always go back to Super Mario World, and Kirby's Dream Land, and Mega Man 2, and Sonic Adventure 2, and others, again and again, whenever I feel like it, until such time that I can't hold a controller any more, because I want to again experience those specific games that I love so much.
I know that you don't feel that way personally, but I hope this helped you understand why others do.