At slightly greater length: cryptocurrency has no legitimate uses not done better by other parts of the financial system. It is designed to be proof against legal recourse (and should be illegal for that reason alone); as a result it is perfect for ransomware, other extortions, and scams of all sorts. (The very first “smart contract” on Ethereum was for a Ponzi scheme.)
Like penny stocks and tulip bulbs, when someone tells you a thing is “sure to rise”, it already has risen. If you buy, you become the bagholder who converts the thing with no intrinsic worth back into real money. You may, if you’re lucky, find an even bigger sucker to sell to.
Buying cryptocurrency is a whole lot easier than selling it. Funny, that.
And that’s even before you get to the vile waste of energy that’s proof-of-work: bitcoin currently uses more energy than Hungary, in order to support 3-7 transactions per second.
Blockchains themselves are not entirely without use – for example the
git version control system uses them. But if someone says “our product is on the blockchain”, slap them and leave.
For much, much more:
(Disclaimer: David’s a friend.)