I would guess hoarding stuff is an instance of humans' general tendency to become more conservative (in this case in the most literal sense) when they feel reso

I would guess hoarding stuff is an instance of humans' general tendency to become more conservative (in this case in the most literal sense) when they feel resources are scarce. So someone who's poor by choice, like a grad student, would be less likely to. Whereas someone who grew up in an atmosphere of scarcity might be inclined to continue to hoard even if they later became rich.