>>714942152
Most people don't play even half of their libraries for several reasons: either you buy a bundle and only wanted 1 or 2 of the games (but the bundle was cheap enough for it to be worth it), or you bought a game but your life gets busy and have no time for the game, or buy a game on sale "to play later" and lose interest, or you buy a game you know is going to be delisted from steam "just in case I want to play it later on", you might buy a game that you already played on a different platform just to support the devs, etc.
I have a bit more than 1000 games on steam but have only played a bit less than 600 of those. Most of the non played ones are one of the cases above, mostly the bundle case.