D&D economics are silly.
Two adventurers are walking down a tunnel, and they come across 100 gold pieces.
The younger adventurer says, "Hey, look, it's 100gp!"
The older adventurer shakes his head at the younger adventurer, and scoffingly replies, "That's nonsense. If there were 100 gold pieces in the middle of a tunnel, someone would have already picked it up by now."
The Efficient Campaign Hypothesis.