The volume of transactions and amount of money involved make the "Dark Web", cyber-criminals, crypto exchange hackers and other bad actors look like amateurs.
This isn't because Bitcoin is pure and inherently repels criminals from it, it's because it's generally not well adopted, even among criminals. Plus, privacy is far from perfect now, so moving large amounts of money and not getting detected later would be quite hard. But Bitcoin has privacy improvements in its roadmap, so if we imagine that Bitcoin would one day be as popular as banks, than all the criminals will switch to it too. And if Bitcoin will not get more popular, than there's really no point to be happy about banks helping criminals.