I think the present culture of indulging in nearly unmitigated crypto-Utopianism is the more interesting concern. It's becoming difficult to argue against cryptocurrency in the tech industry without some form of rebuke enumerating the various potential applications (none of which are in dispute, generally) and/or incoherently equating cryptocurreny to the internet or other such developments (in this story, the future will render skeptics little more than 21st Century Luddites). For an industry so predicated on logic, it's kind of alarming to hear such blatantly shallow reasoning. The militant proselytization of cryptocurrencies often verges on absurd. We should be actively challenging and questioning our beliefs about something that has attracted so much attention and money.

All that said: cryptocurrencies might succeed. No one can outrightly deny the possibility. We should stick to arguing as to the likelihood or the extent of 'capture' it might achieve.

The forest for the trees that the more devoted crypto-Utopianists are missing is that cryptocurrencies, and perhaps the blockchain concept more generally, are at present an inferior or nearly inferior mechanism on almost all of the dimensions we should care about: speed, convenience, stability, cost. Put in short, a commercially-motivated centralized actor, backed and regulated by one or more government authorities, will always be able to perform as well or better on most of these dimensions than cryptocurrencies, no matter how many improvements are made to the system. We usually then end up asking if that system is problematic or should be challenged. In the first world, there aren't presently enough people of a subversive mindset to prefer cryptocurrencies to a centrally-regulated system solely on the basis of anonymity, complete transaction transparency, and decentralization (the principal advantages of cryptocurrencies). That could change, but it seems fairly unlikely. Importantly, I'm not taking a political stance here. I'm instead trying to account for human behavior.

Cryptocurriencies are nevertheless valid stores of value. People have relied upon all sorts of things throughout history to store value, because achieving the designation is as simple as getting some people to trust in a particular system. But the thing about stores of value is that they inevitably offer variable degrees of reliability and trustworthiness over sufficiently long time horizons. It would be foolish to argue, for instance, that the US dollar will remain the predominant global reserve currency in perpetuity. What we can argue with a higher degree of certainty is that the US dollar is unlikely to experience a catastrophic, abrupt decline in its trustworthiness. I would posit that the same cannot be said for cryptocurrencies and the primary reason for this is that some substantial proportion of their value is likely baked on purely speculative behavior (the volatility suggests as much). A secondary reason is, ironically, that there is no central authority to intervene in the event of a panic-induced selloff. And the real problem is that there will always be stores of value that are relatively more trustworthy, according to the public at large. The average person can see and feel gold. They understand that it's a store of value and history reaffirms their conviction. They don't have to comprehend very complicated technical and economic dynamics to believe in gold. Now you might argue that cryptocurrencies can remain stores of value without realizing broad adoption and I wouldn't contest that. But the risk exposure they present, relative to other available stores of value, seems at the very least problematic.