Illicit plus grey market and a few special cases. Fine, you win the Pedant's Prize for nitpicking. The point is that they don't make a good general-purpose currency. Just because they're awesome for buying drugs and secret VPNs doesn't mean very much in the grand scheme of things (most transactions, at least in the developed world, do not take place in the grey market).
Also, just because some people do something doesn't mean that there aren't strong incentives against doing that thing, and doesn't make a statement such as "people don't do that" false. It just means that there are exceptions, but when the exceptions don't affect the point it is common to ignore the exceptions in general conversation.
Also, just because some people do something doesn't mean that there aren't strong incentives against doing that thing, and doesn't make a statement such as "people don't do that" false. It just means that there are exceptions, but when the exceptions don't affect the point it is common to ignore the exceptions in general conversation.