Maybe they are but I've never seen evidence for it, even though there was plenty of evidence for drug traffic. It's easy to make an evidence-free claim that can't be proven false, but that doesn't mean the claim is true.
> Maybe they are but I've never seen evidence for it,
That's how money laundering works. The criminal says he accepts a token as a payment method for an illicit deal, and states where these tokens can be purchased for a fair price. The customers proceed to spend their cash on these tokens to then perform the transaction on the black market. Subsequently the criminals sell these tokens for cash to their next customers. That's how Japanese organized crime launders their earning with pachinko parlours, that's how drug dealers in the US use Tide detergent, and that's the only real-world use of these so called "cryptocurrencies" such as bitcoin.
