Nearly all the times when a fiat currency "dies", it does so by people simply converting all their money into its replacement. More often than not, there's even a nominal equivalence between the old and new currencies. Describing this process as "death" is just sensationalist.

The cases where a fiat currency disappeared and left its holders without nothing are so rare that they make it into high-school history books.

That's surprising and quite alarming, I would've expected it to be at least a century

There aren't many (any?) century old fiat currencies so no way that would be the average.

Clearly that's the case, but I didn't expect it to be.