No doubt it comes from other places but those are the main sources and it would be like cutting the head off the snake imo.
I remember reading an article - here's the link. It talks about both of our points. (just an fyi- we both have some validity). Reduction in drug distribution, has reduced the numbers and cut into their profits but the violence is still an issue.
Legalizing Drugs Won't Stop Mexico's Brutal Cartels
"But would legalization really work? With each day that passes, it looks like it wouldn’t be enough, for one overarching reason: The cartels are becoming less like traffickers and more like mafias. The
cartels are becoming less like traffickers and more like mafias. Their currency is no longer just cocaine, methamphetamines, or heroin, though they earn revenue from each of these products.
As they have grown in size and ambition, like so many big multinational corporations, they have diversified. The cartels are now active in all types of illicit markets, not just drugs.
The legalizers, a group that includes former heads of state from Brazil, Colombia, and Mexico, largely agree with this comprehensive approach. Trying to cut supply without cutting demand is a losing game, they argue. Their recommendations call for the normalization of drugs (that is, legalization of possession linked with public-health regulation), including cocaine.
That would almost certainly hurt the cartels, but it probably wouldn’t be enough, counters Mazzitelli of the UNODC. "Legalization is a fake solution to the problem of security,"
Worldwide, the cocaine market today is worth about half as much as it was just 15 years ago — $88 billion compared with $165 billion in 1995.
This would be excellent news — if it weren’t for some alarming trends going in the other direction. As
the cocaine trade through Mexico has fallen dramatically, the violence here has risen remarkably"