I've known some folk. From weed to cocaine.
They absolutely do this.

Independent contracting, roofing, concrete, etc. Oh. And farmers. Lots and lots of farmers. Easy to wash money.

They have the best/shadiest lawyers who absolutely know what's going on. They are paid very well.

They live fairly modestly. Dress smart, not flashy. They don't show off or draw attention.

They're smart.

They don't fuck around.