I’m sorry but to clarify a few points here, Bitcoin “works” technically, and it works as a speculation and black market vehicle. It has not replaced the US dollar. I don’t see people having a need to use it when shopping groceries, paying for concert tickets, etc even when the option to do so is there.
The comment I was replying to was about technical problems, like high gas fees.
You can use fiat for speculation and black markets.
It would be weird to define "crypto works" as "people have to use it for shopping". It would be nice to be able to use it with more shops, but that is another matter. I know people who keep their savings in crypto and pay with credit cards that are backed by crypto.
Whether you "need" for example becomes an ideological question. If you agree with governments monetary politics, I guess you don't need it.
This is precisely the authors point.