This is just a silly concept, by name. The whole argument is flawed.
With a boxed copy, I own that box and game disc. I can break the game disc, use it to play the game, etc.
With digital distribution, you do not own the game; you have a license to use the game on your system.
The real name for "trading digitally distributed items" is actually called RENTING! And you do not need an economists to explain renting to you.....
I am free of all prejudice. I hate everyone equally.
- W. C. Fields