I am going back and forth in my thinking on whether cryptocurrencies are a fraud. Of course there are obvious scams in this area that try to directly lure people out of their money; those are not what I wonder about, but the digital currencies themselves.
There have been frequent reports of market manipulations over the years and the whole setup looks like a pyramid scheme where the early "investors" get rich at the expense of the late suckers. Plus, some of the prominent people do, while certainly being brilliant, come across as charlatans. Fun to read and often insightful, sure, but I cannot shake that vague feeling that something is off.
On the other hand, cryptocurrencies have been around for while now and not collapsed yet, in spite of the occasional scandals. And where the line between "pyramid scheme" and "positive-sum game" should be drawn, is not clear to me. The whole economy has made humanity so much better-off since growth convinced people that the cake is getting bigger and that things can get better for everyone, in contrast to a zero-sum situation.
So maybe Bitcoin and the like will stay around, and we have to get used to that. To the moon!
(And as a side note: Whenever someone argues for a blockchain to be used anywhere else than cryptocurrencies, feel free to roll your eyes and laugh them out of the room.)