There's limited evidence that demand for currency is really related to the underlying material it is printed on. In fact, that has been a staple of our economy

There's limited evidence that demand for currency is really related to the underlying material it is printed on. In fact, that has been a staple of our economy since we adopted fiat currency. It is not perfect to have fiat currency, but currency value is more about aggregate demand for goods and the functional circulation of the existing money. (See velocity theory of money). Remember also that the laws of supply and demand are not necessarily rational, and they effect the value of gold just as much as the value of paper money. (Gold is not inherently valuable)