It makes much more sense when you imagine money launderer's money and your money having the same value in those dealers, but having different value for their ho

It makes much more sense when you imagine money launderer's money and your money having the same value in those dealers, but having different value for their holders. You, a law-abiding, legitimate buyer, have paid all your taxes and committed no crimes on that money. You can do with it whatever you want to, so for you, it's one to one, a dollar for a dollar. For a money launderer, however, the money is a hot potato. There's still a probability that it left a trail going back, so, he's not so free to use it as he pleases. It's basically very similar to counterfeit money in that regard: it's value to it's holder (who knows about the risks) is much less than a "real" dollar for dirty money dollar.