I don't know much but here are possibilities in mind.
Pay those Bitcoin for cash guys, who mail you money... But that cant be used to do millions. Also, you could probably convince that guy to hand over their address.
Cash out in Russia or somewhere shady....
What else?
Also on top of angry drug dealers, I assume LE can subpoena any regular cashout service...
What happened to the older market exitscammers? I assume they are going to sit on their btc for years till attention dies down?
Someone should create a bot to monitor and alert people whenever there is activity in these wallets.
Also, I looked at the Blackbank wallet explorer and did they deposit like 0.0001 BTC in hundreds of different wallets?
Whats the end game?
You can monitor the addresses but so what? It starts moving and will move forever but you don't know at which transaction the owner cashed out.