See:
There Is No Escaping History. Fiat Currency Eventually Fails.
Notice that this is a critique of fiat money -- not a critique of state-issued money under a gold/silver or other standard. Fiat money is a rare occurrence in modern history. (We live in strange times!) As we can see, the examples found by the author are a small number of short periods here and there.
I have my own critique of gold/silver standards, but that's another issue.
Paper money created with no back up asset and just trust on government. Maybe thats why fiat money always reduced the purchasing power value. Central banks always print paper money to boost economic growth but inflation always increase