The number one drug money launderers in the world are large banks in The US. They have been fined multiple times for just such.

I feel the biggest fault in people's brains about drug trafficking is scale.
It is because people watch shows (starting with Miami Vice) where the drugs are a few suitcases.

The reality is tractor trailer loads.
C-130s flying in weekly with full loads.

We are talking so much money that $1s are left to rot in piles.

And the only group big enough to handle money laundering at that scale is the too big to fail banks.

There isn't enough bitcoin being traded yet to put up with the drug trade.