I thought I had too many with 25 new books of maybe 20$, 25$ each, but apparently I have very few books for a chessplayer

I only *really use* about 5 of them, *use* maybe 10 of them occasionally, and seldom looked into the other 10. I mainly have opening books and mainly use them as a reference, when preparing for opponents, or just before a chess game, to see what the theory was again. Only a few of them really taught me openings from scratch; The Scandinavian, The King's Indian Defense, The Morra Gambit and The Sicilian Dragon I learnt from the books.