You don't become a hero for the money. The money's nice, sure, but you become a hero because something inside compels you, drives you to it. Defending people from monsters simply doesn't pay well enough to make it a good career move.
As for hunting dragons... well, the money is usually good, but the job really bites.
A group of five professional heroes goes into the lair of the dragon. Who will win?
Spoiler: The dragon.
But it turns out killing a hero sometimes does nothing more than make him even more determined.
Sometimes, heroes are never more dangerous than when they're dead!