I do think there are use cases for public, decentralised blockchains today: those having to do with moving #wealth across time, across space or between people, in an ethical way, when unjust laws prevent people from doing so, or when the other mechanisms are too inefficient or burdensome:
I think there will be other legitimate use cases sometime in the future.
For instance, notaries and other public institutions are very slow and expensive ways to keep track of property and of voluntary agreements. Blockchains might help there. On the other hand, we don’t want everybody to know who owns every single vehicle, apartment or plot of land, and non-reversible transactions sounds like a dangerous idea when one’s spending their life savings on a house. So it’s unclear.
(Still, a problem with that: you have to hold certain political positions for those use cases to look “legitimate”.
For example: you have to find unjust what the Canadian government did to economically suffocate the protests of the truckers. Or you have to agree that it’s justified for law-abiding citizens to do whatever they can to prevent the State from seizing their assets.
I am more or less there, and so I see blockchains as a benign tool for all that.
I’m not saying one has to be a hard-core libertarian. But a dash of individualism and scepticism towards States is necessary to see the merits of blockchains today.)