I'd say it's varied & most often a combination of multiple things.

- They want the cover art

- They want a physical token representing an artist they like

- They want to financially support the artist in a direct way

- They speculate they might get a player someday (much akin to book buyers leaving books on their shelves unread for years on end)

1 of the above might be the primary driver for any given buyer but I'd assume all of the above play some part in their motivations.