99.9999% of everything is done using fiat, so of course it will be true for crime too. What you should look for is relative amounts, like percentage of criminal transactions on the network. I'm sure this is higher for Bitcoin than it is for banks, because with all the KYC and financial monitoring, it's just harder to move big amounts of money. Or take ransomware for example, Bitcoin is already a dominant payment method there. I think the criminal use of Bitcoin is something that we should just acknowledge and accept, there's no way to have both privacy and control over your money without having criminals attracted to it.