What I was saying is that, given how much money comes in from drugs, they are already able to own plenty. Even when drug money can't be spent freely or things done openly. If drugs are legal then 100% of the money is available freely to a handful of people from cartels, who may even own a significant % of Mexico's Gdp. I'm imagining a situation similar to Italy, there are articles on the Naples trash monopoly owned by the mafia for example. With so much money, cartels can easily own larger industries in Mexico and I'm not sure that's a good thing.

I don't think you understand what's being discussed when people talk about legalization in the US. If the US legalizes, the cartels are not going to be the ones supplying drugs to anyone in the US. Legalization in the US will not legitimize the cartel's business, it will destroy it.

Usage rates of marijuana in Mexico are one tenth the US, and Mexico has one third the population. Without the US black market, the cartels' revenue will be reduced to just a couple percent of their current intake.

I've read quite a bit about the situation in Italy as well. It's not easy to compare what happened to Italy with what's going on in Mexico now. The Cosa Nostra were never dependent on drug or smuggling revenue in the same way as the Mexican cartels are currently. The US military directly supported them as part of the invasion of Italy in WW2. After the war during reconstruction, Cosa Nostra was able to monopolize nearly all construction revenue in southern Italy and integrate itself into every corner of Italian government and public life. The Mexican cartels are terrifyingly powerful, but they are nowhere near close to that yet.

He does have a point though, that they may get there eventually.

I don't think the cartels will disappear overnight, either. But they will see a large chuck of funding dry up, and it will then be easier to after them for their previous crimes as well as whatever they get into next.