Because the pieces of paper aren’t backed up by gold. If a piece of paper was just a token representing a piece of gold, then the price of gold (in pieces of paper) would never change.
Of course, you can’t eat gold either. There’s a very long chain of inference between actual use of things and the various exchanges (often theoretical) to get to a value. “value” is fundamentally what you’d give for a thing you don’t have or what other people will give you for a thing you do have. It’s not intrinsic to any good or currency.
Because the pieces of paper aren’t backed up by gold. If a piece of paper was just a token representing a piece of gold, then the price of gold (in pieces of paper) would never change.
Of course, you can’t eat gold either. There’s a very long chain of inference between actual use of things and the various exchanges (often theoretical) to get to a value. “value” is fundamentally what you’d give for a thing you don’t have or what other people will give you for a thing you do have. It’s not intrinsic to any good or currency.
Food and Water seem valuable.