For instance, people claim that cryptocurrencies have real utility, and cite their use of moving money out of countries where traditional international currency transfer is difficult. While that is true, since the function of those transactions is to use the currency as a medium of exchange of other currencies it cannot explain the volatility of the exchange rate, as the current exchange rate is irrelevant if your purpose is simply to convert to and from other currencies.
The volatility is due to speculation, but without real utility it is difficult to see what anyone could be speculating on. One could say "belief that the value of the currency will continue to increase", but that's essentially admitting to it being a pyramid scheme. If people ever stop believing and refuse to buy, which would be easy to do since it is nothing to spin up another coin, the price collapses.
Now admittedly I am not an economist, so I make no claim to the correctness of my assessment other than that it makes sense to me. However, the vast majority of people pushing cryptocurrencies aren't economists either.
I’d be more skeptical of the moving money around hypothesis but I know people who looked into it when thinking about leaving the US. So at least people are honestly looking at bitcoin for that purpose, even if it may be impractical.
I still think cryptocurrencies are largely an experiment in the application of contemporary memetics to scam people, but I have to admit that said experiment has produced wildly more successful results so far than I had ever anticipated. The power behind the convergent desires of get-rich-quick schemers, true believers, conspiracy theorists, anarcho-capitalists, and complexity fetishists is a pretty terrible thing to behold. My prediction would be that this particular maneuver won't work because only just over one of those groups really have any interest in its success (believers and some schemers). Then again, all my other predictions about cryptocurrencies have been wrong so far.
[0] I took advantage of a hype cycle to make ~$1k. I kinda regret it because in a small way my greed-driven maneuver contributed to the current state of BTC and its ludicrous energy usage.