Fiat circulates because people do not value it

We know from Gresham's law that bad money drives out good from circulation... that if people are able to pay for their purchases with a form of money which is overvalued then that money will flood into circulation. People will hoard the undervalued (or real) money and spend the overvalued (or fake) money into circulation so that they retain what they think is the more valuable form of money. This partly explains why fiat money is the predominant form of money in circulation today. We know that people do not truly value fiat money otherwise it would be hoarded and not circulate so widely. The fact that fiat money is in use... somewhat paradoxically... shows that it is both valued and not valued. (It is less valued than the other currencies.) People value the currencies they do not spend more than they value fiat money. Fiat currencies are valued the least of all the currencies and we know this because they circulate widely in the economy. People do not spend what they value.