The Giant Dragon's outer scales were extremely hard; they did not like soft things for their nest, but instead, gold and diamonds—which were hard yet not easily crushed—made the most comfortable beds for them. Moreover, gold and diamonds could polish their Dragon Scales, making them even more sturdy and shiny.
Sturdy, to be ready for combat and to maintain an indestructible body.
Shiny, to attract the opposite sex, which follows the same principle as humans liking to wear various beautiful garments.
The saying that a Giant Dragon's cavern is the richest is absolutely true.
"Winter is coming, and the Giant Dragon should be foraging everywhere to stock up food for winter,"
"Then we'll just wait it out. Wait for it to leave, and then empty out its treasure cave!"
