Earlier quoted context omitted.
Tell me, what assets exactly are backing BTC which stop it from crashing just like Luna?
LUNA minted trillions of brand new tokens within the span of a day or so rendering the token worthless. This is due to the way LUNA was tied to the algorithmic stablecoin UST. It was a true ponzi. BTC's max supply is capped and the release schedule of new coins is fixed and predictable. There is no possible way that trillions of new bitcoins could suddenly be created.
Fiat currency has the backing of a government. The government demands certain payments of this currency in order to own land, and also for some extra rights like mineral extraction, fishing licenses etc. Thus, as long as the government is viable and can confiscate the land of those who don't pay, there will be demand for the currency, and it will be proportional to the value the government assigns to the property and the rate of tax.
Thus, the currency is stable, because you know at the end of the day, there will always be a buyer who needs to pay their taxes.