Black Swan author urges: “Use cryptocurrencies ”

There are two steady-states of money, both described by the money supply equation PQ = MV from macroecon-101. If everybody uses dollars, Bitcoin is worth nothing and the value of dollars (1/P) = real GDP (Q) / MV, real GDP rises at ~1-3%, velocity of money is roughly constant, and so price levels go up at the ratio of money supply growth / real GDP growth. The same goes for crypto - if everyone uses Bitcoin, the dollar is worth nothing and prices of goods go up based on real GDP / Bitcoin money supply growth, with the value of Bitcoin (in goods, because nobody would be using dollars) as the reciprocal of that. Cryptocurrency inflation is actually a lot more stable than dollar inflation, because the supply of a cryptocurrency is algorithmically baked into the software itself at the time the crypto is launched. Short of forks and competing adoption, you can predict exactly how many Bitcoin there will be (21 million) when the last Bitcoin is mined (2140).

The wild price swings happen because you have two interacting user populations. If say 0.1% of the population uses Bitcoin and then a bunch of news stories come out about crypto that raise awareness to 1%, then you have 10x as many people fighting over the same supply of crypto. That'll drive the price up 10x (actually more, because people tend to hoard rather than sell when the price is growing up). Similarly, if half those people give up and go back to dollars, the price will fall by 50% (actually more, again because of the presence of Bitcoin hoarders).

In the end state, where everybody uses cryptocurrency, the price of crypto in dollars becomes meaningless, because nobody uses dollars anyway. That makes cryptocurrency a funny investment where its true fundamental value is either zero or infinite, and the price you're getting in the spot market at any given time is a reflection of how likely the public at large thinks these two outcomes are.