I'd say i have 1/4 unplayed games, maybe little less because I have many games that I played before steam started tracking gametime. But most of those are from family share anyway. I find it insane how some people just buy games and never even install them.

And I know there is no way I would be getting anything back if steam suddenly shut down, you are effectively buying a licence to play anyway instead of full ownership. But this is the world we have to put up with and steam is the least shit thing about how game industry works nowdays. Without steam I effectively just couldnt play games by now, which is also kind of troubling. Though if steam never existed and there had been nothing like it, managing all the games would have been nightmare even if you ignore updating them.