There's plenty of valid criticisms against crypto, I feel like they've picked some of the weakest ones. > cryptocurrencies are used because people think they will one day replace traditional money Maybe a tiny minority, sounds like a strawman. > a contagious story in which people believe because other people believe in it Isn't fiat the same? Money only has value because people believe it has value / will have value…
Fiat is slightly different in that the government can guarantee a certain level of demand for it by requiring taxes to be paid in it. If you you don't like jail and have a tax liability in US, you can't think dollars are worthless.
Except in the last case, if you use your own keys, you have a choice of either going to jail and keeping the money, or giving it away in exchange for your freedom. In all other cases the only option to hold on to the property - is successfully physically fight with law enforcement to defend your rights to the property (which is quite futile for the most of us).