Correlates with my experience. Sometimes sales are so attractive you buy several games for cheap, or even an entire franchise, but playing them all can take enough time that another sale comes again. Red Dead Redemption 2 has been collecting digital dust in my library because I'm still playing Fallout 76. I stopped buying more because it feels wrong.
Bundles contribute a lot too. Hey you can get these three games for dirt cheap because you own another game in this bundle! One of them’s interesting to you, maybe even already on your wishlist, the others are not, and the bundle is less than the full price of the one you think might be neat. The others just sink to the bottom of your collection, uninstalled, unplayed, unloved.
I know, but I can't deal with two massive RPGs right now. It doesn't help that a multiplayer RPG like Fallout 76 multiplies the role playing opportunities.
Ditto. I have several games in my backlog that I got on deep discount, but need serious time commitment to play. It's going to take me a little bit to play Witcher 3, Disco Elysium, or the entire Mass Effect trilogy. Also there is a certain time horizon on steam that play time wasn't tracked. I am pretty sure I played Half Life 2, since that's why I have a steam account in the first place.
Edit: You may not want to know if your steam account is old enough to drink...
I uses to collect almost everything, now having over 2000 games. Now i select them for Steam Deck playability. I still hoard a lot, but i also try to at least start them once and play a little before moving on to the next one :)
I've bought entire publisher catalogs on summer/winter sales years ago. Tons of games, while I might primarily be interested in a handful. It was just cheaper to buy the whole catalog.