To a certain degree, like with many wildly held beliefs, dispelling biggest cryptocurrency zealotry becomes a whack-a-mole game: of the thousand disprovable beliefs, any given person presented with any given disproof will claim "Well I certainly don't believe that, so you've not done anything against my specific (possibly shifting) 17 beliefs".

In particular, re: "Nobody serious says that decentralization == privacy" -- this is presented as tautology on regular basis, by people that certainly hold themselves as serious and I'm willing to take as such, on Hacker News and other IT-related forums, as well as many other venues.

"Are people suggesting that new economics are needed? I don't think most people are suggesting that" - a lot of more zealous cryptocurrency supporters are very much on the "this is like nothing we've ever seen before" bandwagon, and/or are explicitly desiring as a goal/hope a massive disruption of economic and financial systems.

Just like, if there are N Christians, there are in my experience N+1 Christian belief systems, so it appears to be the case for cryptocurrencies. People more patient than myself are trying to make a dent by tackling those N+1 arguments, hopefully cognizant that for any set of believes P, they'll be presented with those exclaiming set of beliefs Q which obviously has nothing to do with P, those people into P are deluded/irrelevant, and they would never agree with them (unless it offered them temporary advantage:).