When you make a lot of money, the number you see in your account starts to become part of your identity because it differentiates you between you and the people you see every day. The same way if I had blue curly hair, that would become a defining factor of where I “differ” from the general public. The numbers in one’s account becomes an obsession-point.
People get obsessed with the number and how much bigger they can make it. It’s like hoarding. No amount will ever be enough. And once you’re able to buy anything, the actual value of that money becomes meaningless. So even more drive to bring the number up because that’s the only novelty you are getting.
That and power.
Wand of paralyzing. Just tell them that. Then, when they get to use it, they find out that the wand actually just paralyzes itself and just floats in the air doing nothing. DM got me good there just as I had to perform a spell on a guard. Had to aggressively improvise afterwards.