In my games, dragons are pretty darn rare and thought to be unique.
The 'Red Dragon' is a centuries old ruler of a mountain kingdom of kobolds and fire giants, with mameluke-style slave armies of hobgoblins, and a court filled with his consorts and many generations of his half-dragon or dragon-blooded spawn. If his armies take loot, they carry it back and bring him a share.
The 'Blue Dragon' has no known minions, and is an elemental force of nature that terrorizes shipping lanes, sinking ships, raising storms and basically wreaking havoc. Not only is she not known to take treasure from the ships she sinks, she isn't even known to eat anything. She just appears in the sky, trailing thunderclouds in her wake, destroys everything in sight and then flies off.
The 'White Dragon' is served by Frost Giants (although the Frost Giants have a different view of the relationship, seeing the White Dragon as a wild attack dog that they keep happy with sacrifices of food and treasure, giving them a massively powerful, but barely controlled, weapon). It's only concern is food, and it usually hunts mammoths and whales, as it's hunger is never-ending. Any treasures that it's giant 'servants' give it is ignored, and ends up rimed over and buried in ice.
The 'Green Dragon' is all but unknown, even among her servants, at least, not known to be a dragon, as she lives as the immortal elf-queen of the Singing Woods, surrounded by her sycophantic court of minstels and courtiers and advisors and socialites. They flutter and dance for her pleasure, and intrigue and gossip and tear each other down for her amusement, a people so long rotted away in spirit as to be inconsequential politically, and yet convinced of nothing so much as their own grandeur. Her treasures are vast and ornate, sculpted by the generations of elven suitors who have come before her, dazzled by her grace and wisdom, and, like their fathers before them, poisoned in mind and spirit and flesh alike by her breathy whispers.
The 'Black Dragon' lives in a blighted swamp, served by savage tribes of lizardfolk and also by hordes of undead. As with every dragon save the Blue, anything he wants carried home, is carried home, and he doesn't have to lift a scaly claw in the process.
I'm not a big fan of the flying lizards of the Realms, who get blown out of the sky by the dozens during the average Dragonrage. How they get treasure home is beyond me. Perhaps local cultists agree to carry stuff for them...