I think people who are into crafts. They have all of these yarns, construction papers, various tools and stuff. All so that they can say that they have all of these projects in mind that they want to do. But they never do them so they get more crafting stuff and it just eats away storage until their place is practically consumed by it.
Yeah collecting instruments, parts, strings/reeds, and accessories is totally part of it. People hoard to varying degrees but any hobby requiring physical objects is hoardable.