In fact, dragons are important stabilizing influences in dungeon economics. The hoard of gold isn't inflationary until the adventurers liberate it and start buying wands and stuff.
Reminds me of something I read years ago about how Ultima Online would create "gold sinks", super expensive items that served no purpose other than help remove gold from the economy and prevent inflation.
I guess the trick there is they don't spend it. The money leaves the virtual economy. IRL that's impossible.
This is a problem with all kinds of virtual world economies. Players accumulate so much gold that some substitute becomes more useful. Diablo II had the Stone of Jordan, for example.