Eu gostaria de comentar, mas não posso. A passagem no Silmarillion que descreve o primeiro Dragão criando o primeiro tesouro de ouro é este, em "De Túrin Turambar":
But Túrin passed away on the northward road, and Glaurung laughed once more, for he had accomplished the errand of his Master. Then he turned to his own pleasure, and sent forth his blast, and burned all about him. But all the Orcs that were busy in the sack he routed forth, and drove them away, and denied them their plunder even to the last thing of worth. The bridge then he broke down and cast into the foam of Narog; and being thus secure he gathered all the hoard and riches of Felagund and heaped them, and lay upon them in the innermost hall, and rested a while.
Nenhuma explicação de qualquer tipo - parece ser apenas algo que eles fazem. A única coisa que vale a pena mencionar seria que os Dragões de Tolkien são muito astutos e orgulhosos, então a ganância não seria tão estranha em tal personagem.
Também não há explicação sobre por que eles foram criados dessa maneira:
[...] But thereafter there was peace for many years, and no open assault from Angband, for Morgoth perceived now that the Orcs unaided were no match for the Noldor; and he sought in his heart for new counsel.
Again after a hundred years Glaurung, the first of the Urulóki, the fire-drakes of the North, issued from Angband's gates by night. He was yet young and scarce half-grown, for long and slow is the life of the dragons [...]
Então eles meio que surgem.