Well first of all it wasn't the original commenter who made that statement, then they said that some things are banned because the negative externalities outweigh their benefits, though they didn't specifically make any argument as to why cryptocurrencies are one of them and in fact chose poor examples where the ill effects are not externalities at all but the intended function of those banned things (which incidentally is where I entered the conversation to contest), and finally in context we're talking not just about cryptocurrencies at this very moment, but also the costs of losing all benefits of the underlying technology, which includes benefits currently being worked on and those not yet imagined.
But that all being said, the ability to trustlessly transmit value is, in my opinion, already more beneficial than any negative externality associated with any cryptocurrency. Indeed, the very reason that criminal enterprise has adopted cryptocurrency rather than just bartering illicit materials is specifically because the technology is useful for so much more. I for one would much prefer two consenting adults to exchange drugs directly rather than going through an organization with advanced money laundering operations which undoubtedly begets more frequent and more violent crime. All those complaints crypto-fanatics have about legitimate financial institutions apply just as much if not significantly more to illegitimate ones.
But while I believe that to be true, that's not a hill I'm willing to die on. Getting back to the conversation at hand, my point was that, unlike human trafficking or pedophilia which are evils unto themselves and should be banned even if they produce the occasional beneficial byproduct, technologies like cryptocurrencies or the internet are tools which are not inherently bad and which we all use despite the capacity for abuse. Using a baseball bat to break kneecaps does not make baseball bats evil, and the idea that baseball should be banned to prevent the misuse of baseball bats ought to be considered absurd. Trying to regulate something which is at most a loose proxy for the problem you actually want solved leads to numerous problems in practice [0], but it is also wrong in principle to freedom and prosperity to the many because you are incapable of dealing with the abuses of the few.
But that all being said, the ability to trustlessly transmit value is, in my opinion, already more beneficial than any negative externality associated with any cryptocurrency. Indeed, the very reason that criminal enterprise has adopted cryptocurrency rather than just bartering illicit materials is specifically because the technology is useful for so much more. I for one would much prefer two consenting adults to exchange drugs directly rather than going through an organization with advanced money laundering operations which undoubtedly begets more frequent and more violent crime. All those complaints crypto-fanatics have about legitimate financial institutions apply just as much if not significantly more to illegitimate ones.
But while I believe that to be true, that's not a hill I'm willing to die on. Getting back to the conversation at hand, my point was that, unlike human trafficking or pedophilia which are evils unto themselves and should be banned even if they produce the occasional beneficial byproduct, technologies like cryptocurrencies or the internet are tools which are not inherently bad and which we all use despite the capacity for abuse. Using a baseball bat to break kneecaps does not make baseball bats evil, and the idea that baseball should be banned to prevent the misuse of baseball bats ought to be considered absurd. Trying to regulate something which is at most a loose proxy for the problem you actually want solved leads to numerous problems in practice [0], but it is also wrong in principle to freedom and prosperity to the many because you are incapable of dealing with the abuses of the few.
[0] https://en.wikipedia.org/wiki/Perverse_incentive