“Imagine a private party being able to issue currency without any supervision.”
But they’re not issuing currency. It just doesn’t meet the definition.
Even our modern state-issued currency barely meets the definition, and only because it has the backing of a legitimate government who people have some confidence in. Crypto has absolutely no backing at all, so once people notice it’s a mirage, they’re nothing more than collectibles.
That’s my point. It’s not really currency but people are believing that it is, it’s only backing is the integrity of the people running the exchanges.
And we are shocked that for most people their integrity is for sale, particularly when we are talking about huge sums of money involved.