It's like being a broker of dirty money. The cut/commission of the broker is MUCH greater than it is for legal transactions.
Take Soros, for example. He donates to nefarious operations all over the world and does so in ways that cannot link him to the recipient of his generosity. Someone has to provide that service...someone that gets paid handsomely for taking the risk that Soros doesn't want to take.
Money flows to and from illegal activities and from the wealthy to their causes that might be better hidden.
There are brokers who specialize in those kinds of transactions.
I think Epstein was funded by one or more state actors.
If so, that involvement would also explain why so many countries, their LE, financial regulators, and tax agencies turned a blind eye for so long.