Do you really think there is a limit to man's desire for pleasures, no matter how illegal or damaging? I don't.
Yes. The wealth and power of the cartels is testament to the fact that there is certainly a large demand for those sorts of things. But it is not limitless, and the cartels are subject to the laws of supply and demand like everyone else.
What IS limitless is the desire for wealth by the cartels. It is not credible to argue that there are billions of dollars worth of untapped criminal activity that they could be exploiting now, but for some reason are not.