The film is going to be projected anyways. You are buying the right to be present in the room when that happens. You can transfer that right (give the ticket to someone else), even sell it. Before the projection happens, the company might want to close and cancel that projection, in which case you are left without the chance to attend and exercise your purchased service; in that case, the company would (should) refund your full money.

Now change "attend the cinema" with "play a videogame" in those phrases. We should be able to freely exchange games between us. I should be able to sell them to you. The medium (digital, physical) is irrelevant.