He can melt it with his fire and pour it into moulds, for jewelry etc.
Why would a Dragon want GOLD? He can't eat it, drink it, smell it, wear it and certainly can't spend it.
It's pretty and shiny! Dragons are probably just really into home decorating.
You could be wrong, Jan. According to my friend, Chris Dews. Dragons do indeed eat gold.
Chris (better known to Asklings as Waldorff and John O'Gaunt) wrote a novel called The Druid and the Bracelet in which he showed that dragons do indeed eat gold. It's a very entertaining read, as everybody who interacted with Chris on Ask would expect.
Actually ... Dragons CAN spend gold, in a few ways:
1 - They use it to pay their employees. Yes, dragons have employees. Some may call them minions or servants, but dragons have strict employment contracts and pay very well.
2 - They use it to purchase things they want, using go-betweens.
3 - Dragons are magical shape-shifters, remember. So they can actually take human form and spend the gold that way, as well.
So what do dragons buy, you may be asking. Well ... Let's put it this way: When the Fifth World comes, and magic returns (as it does in cycles) - dragons will awaken and everyone will find out who REALLY owns a vast majority of the worlds' stocks and bonds. ;)