...It’s not stamps or coins.
Why can’t it be like stamps or coins? There are certainly many parallels to record collecting. Many of us collectors have "completist" tendencies when it comes to certain artists, labels or genres. When your first twenty Impulse, Trojan Records, George Jones purchases are home runs, you tend to just keep blindly acquiring more, especially if you find them in the dollar bin or garage sales.
Also just like stamps/coins, there’s that thrill of the hunt...finding that rare record that’s been on our want list for years.
As mentioned above, prior to streaming music or youtube, there really wasn’t any way to discover new artists besides buying the record and taking it home to listen to. I used to sell back my (at the time) unwanted records to buy new records, but after many instances of re-buying records a second time, I stopped turning over my collection as much. I might only listen to that Dead Milkmen record once every 10 years or so, but even pulling it out of the stack and looking at the cover brings back memories of youth. Why would I get rid of that experience if I have the room to still hold onto it?
As dpop said above though, really the difference between a collector and hoarder is more of a logistical question.