This is wrong. First, there is no such thing as sound money.

Second, the problem with fiat is that people are saving too much to the point where we have underemployment and in some countries extreme amounts of youth unemployment.

The gold standard failed because the supply of gold was not growing fast enough. The constraints of money creation under a gold standard constrained the maximum size of the economy.

The underlying reasoning behind fiat is that money creation should be driven by demand so that the money supply grows with the economy. A good approximation is that private debt creation follows demand. A growing economy needs loans to finance expansion, therefore creating loans will ensure the money supply catches up with economic growth.

However, the obvious problem is that loans have to be paid back and paying back loans contracts the money supply. If the economy needs $4 trillion and growth ceases then we will actually fall short of the $4 trillion and we will enter deflation and deflation is a self reinforcing cycle that prevents further growth. We are running into the same problem as the gold standard. The money in circulation is not adjusting to the level needed for the economy. The private banking sector as the sole source of money simply isn't enough as it requires lowering the interest rates until you hit 0%. Without negative interest rates the system just stops there. This isn't surprising. Tally sticks [0] function the exact same way as fiat does. There isn't enough silver/gold in circulation so people create a ledger on top of it. When the ledger has served its purpose the two sticks (each representing credit and debit) are united and then destroyed together. A short term fall in growth doesn't imply that we have reached the end of growth. Ending the economy today is obviously a mistake.

What is needed is a secondary method of money issuance in the hand of the public. Direct issuance of money by the government generally suffers from discipline problems. Politicians just can't get enough money and when there is too much of it they refuse to stop, often there are legitimate reasons to not stop. What we'd need is an independent organization whose sole function is money issuance based on a macroeconomic measure that is important even if we don't have real growth right now.

Turns out, what the fiat system needs isn't real growth to begin with. It only needs nominal growth. That is, nominal growth caused by inflation is just as good as real growth as it still stimulates organic debt creation and therefore a demand driven increase in the money supply. As we are merely fighting off a contraction in the money supply, the destination of the issued money is not important, as long as it drives inflation. You can hand the money to unemployed people if that helps to drive inflation.

One unique difference between private banks and public government is that banks require you to return the money via monthly payments. Governments require you to return the money via taxation. This difference means that publicly issued money doesn't have to disappear on a schedule, it only has to disappear when there is too much of it, e.g. you are suffering from too high inflation. An inflation based tax policy could solve this problem.

If we went back to the gold standard we would run in the same not enough money for the economy problem except it would be even worse. Interest rates would have to be very negative. -10% interest probably wouldn't be an exaggeration but then people just withdraw their gold for risk free gains and we'd have no economy to speak of whatsoever.

[0] https://en.wikipedia.org/wiki/Tally_stick