The anonymous whale sent from one wallet to another just to rotate their address? Or have they actually sent this money to someone else? Was this money acquired legally? Is it being used for illegal activity? A Bank would have to audit it at the very least, so there's value for the people at having banks manage that transfer rather than let them do it anonymously.

Also for someone with $166M cost of a large transfer seem negligible even if it was in the 100s of thousands. Unless they need to move it all the time continuously, in which case I'd ask, why do they need that?