This is such a meme'y reply that boils down to pure whatabouism.
What is wrong with search for some comparisons and perspective? Everything has externalities, let's compare them to see how big of an elephant this really is.
Nothing's wrong with it. But the fact that this paper looks at a specific different piece of the puzzle doesn't make it bad. You're just asking for an entirely different piece of research, and criticizing this even though it's a step toward being able to make that comparison.
And then $'s spend on armies!
Because if the US adopted BTC, we wouldn't need an army at all? Is that the claim?
The US spends a lot of $ on waging war, $ that could have been spend on Healthcare, or funding initiatives that help combat climate change. I'm saying Healthcare and climate are hardly a priority for the US, so why is BTC the bad guy here?
Bitcoin takes away the power of central banks to fund wars willy nilly. All the corrupt forces that suck at the teat of free money will coalesce around the protection of this debasement racket and so we get these "think of the kids needing energy" articles...
And include a cost-benefit analysis taking into account that the US dollar does about 100,000 transactions per second, and bitcoin does seven.
Also consider more scalable cryptocurrencies running proof-of-stake.