Let’s talk about Dwarves.
Dwarves are vectors of gold: they can smell gold, they desire gold above all things, they go mad without gold, they are afflicted by the Gold Sickness. And it’s not even like they want gold because it’s valuable (even though it is), it’s like they need it to live (maybe they eat gold? Like Gorons eating rocks from the Legend of Zelda?). It’s a psychological thing, it’s Greed with a capital G, it’s a Big Boy Sin. And there’s never enough gold to satisfy a dwarf. Adding a dwarf to the party is a mixed bag because dwarves are like labrador retrievers: they can smell gold out, but if you don’t keep them on a leash, they’re going to steal it all and shove it in their dirty little mouth and chop off your legs with a handaxe. Exactly like labrador retrievers.
Dwarves come to human lands because there’s not a lot of real estate left for them where they come from in the Underdark. They join adventuring groups because while they can smell gold out they’re not invulnerable to a crossbow bolt through the head.
There are a couple of different game mechanics you can cobble together: there’s Dungeon Crawl Classic’s Underground Skills (Smaller concentrations, down to a single coin, can still be smelled but require concentration and have scent ranges as low as 40’ for a single coin or gem), there’s Dwarven Greed from the always impressive Torchbearer, and I feel confident that Warhammer Fantasy Roleplay had special dwarven madness as a mechanic for their Dwarfs (following the old ways of grammar laid out by Tolkien himself). You might even find references in the GLOG and in some old level tables for Flail Snails content to dwarves and gold.
The Gold Sickness is an actual sickness: as dwarves collect more, gold they get more sick. It makes you ill and it breaks out in scaly rashes all over your body and eventually it breaks all your bones and makes you breathe fire. Dwarves are dragons; dragons are just dwarves at the end of the Gold Sickness. That’s also why dwarves hate dragons, it’s like you going to a nursing home and hanging out with extremely old people: there’s a touch of revulsion and fear because there’s nothing that makes you feel your own mortality than hanging around those who are so close to death. Likewise, there’s nothing more revolting to a dwarf than seeing where his gold lust leads him. He can escape the Gold Sickness just as well as you can escape death.
In fact, it’s so off-putting that dwarves that shut down their Greed usually give in to Wrath, starting for themselves their own little black book full of Grudges. Grudges are a way to hold on to yourself: if you remember why you hate a person, that’s tied to a personal offense, an emotional reaction. And that emotional response keeps you from stripping naked and rolling in a pile of coins and becoming gigantic and scaly. Grudges are the way a dwarf remembers who he or she is. That and fire engine red mohawks.
You either die a banker or live to see yourself become a punk rocker. As all things should be.