A fiat currency is indeed just an accounting unit, but it has some floor against falling to zero, as it can legally extinguish any debt, and is needed to pay taxes.
Even so, sometimes they fall to basically zero. What chance does crypto have when sentiment turns against it?
Generally speaking it has been successful, more so than the gold standard. It's true that sometimes states fail, but that's not something a monetary system can prevent from happening, or insure against.
Sorry to say, but you're deluded. A blockchain is made of "information". Information has no coercive power. A blockchain can't enforce laws. It can't stop illegitimate violence. It can't perform any of the functions of a state. Not even remotely.
Leaving the gold standard has been so successful, as evidenced by the inflation crisis leading to rising cost of living and housing shortages in every western country.
Inflation and a rise in the cost of living are different things. Inflation means an increase in the (nominal) price level, whereas the cost of living is measured in real prices, specifically real wages.
Inflation is an increase in the money supply, which is why it's called inflation - the money supply inflates. I know a lot of government economists like to define it as rising prices because then there is no word for increasing the money supply which is very convenient for them and the governments they work for.
No, it's not just government economists. It's the standard definition in economics. But that's beside the point... the BIG mistake you're making is confusing an increase in nominal prices (inflation, or whatever you want to call it) with an increase in real prices (a rise in the cost of living).
