This is evidenced by the basic physical law - substance remains constant.
People live essentially on goods or materialized items (substances), rather than the paper money although it may trade for goods given it is accepted. What if the money is denied by the goods producers?
It is not a joke, and the reality is coming up.
Therefore, honesty trade is required. Otherwise, there is not winner in the on-going trade war between the USA and other nations.
God is watching what's going on. Thus, hard-working people would be rewarded.