This term "peak fiat" is funny, because ya know paper is a renewable resource, and it's really easy to tack zeros on to the end of a number in a database somewhere for someone really important.
But I suppose everyone just means "peak number of people infected by the fiat mind virus". When enough retirees and their children run out of purchasing power, and their pension or social security won't be able to cover the difference, that's definitely curtains for fiat, and it doesn't look like a peak in monetary terms; the value of all those colorful pieces of paper and zero-heavy ledger entries just nose-dives off the cliff to zilch.