The problem is that math is basically law, and that mathematics follows rules that it does not deviate from. You said yourself that money is an abstraction of human effort that can be traded for the efforts of another, however, there is no actual amount of value that is consistent for the amount of effort and energy output of any given person. That is why get rich quick schemes are so predatory. That’s why billionaires are such parasites. If money stopped having value how many wealthy people could actually start using their labor and exchange for goods and services? How many can cook for someone and clean for someone and rear children for someone effectively?