Expanding on that, and explaining why this is not Digital hoarding, I have a HUGE catalog of games, lots of which came from bundles and such, if I was able to sell back games to steam, even if for a few cents, I would delete a big chunk of that. But as is I have no reason to do it, I can put them in a “never played” category and forget about them until I randomly find a game in the store that mildly interests me and notice it’s already in my library.