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.
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.