Why is this so hard?

I went through some of my CD collection this morning to try to weed out some that I can stand to part with. I have a box of promo singles and a small stack of 9 sitting here next to me that I wouldn't miss if they were gone. The issue is I have probably around 600 CDs. (I'm too lazy to count them.)

I'm sure there are more than 9 pieces (plus the 25+ free promos) in my 4 racks of music that I can bear to sell.

Why is it so hard for me to get rid of these CDs? I hardly even listen to CDs anymore. I could use the money more than I need the CD.

Why can't I part with them?

Is there something wrong with me?

Come on! I have both the clean and explicit versions of House of Pain on CD. Really, when was the last time I listened to House of Pain on CD? It probably wasn't even in this decade. I have CDs that I know I haven't even listened to ever. (Sprung Monkey?)

Does anyone else have a collection of things they don't use, don't need but can't talk themselves into getting rid of?