Presumably OP means deaths linked to the production, distribution, and sale of illegal drugs.

Think Mexican drug cartels, gang wars over drug selling operations, etc.

Ok that accounts for maybe 150,000. Staggeringly high. But I still call Hyperbole on 'millions'

Then add people whose life was ruined by addiction, as producers refined their wares to maximize that side-effect, and by getting caught in the prison system - then died of the effects of poverty, homelessness and emargination that result from those conditions. It's hard to keep stats on that, but you'd easily run in the millions.

Are we still talking about drugs? Or obesity? Or internet addiction? We're talking billions by now. An no war was ever waged on those things.

The 'war on drugs' has not been shown responsible for addiction, addiction-related crime and related social ills.

By forcing producers underground rather than regulating their wares, WOD in practice pushed markets towards the worst possible products and the most harmful situations. We have entire bureaucracies dedicated to ensuring the food you eat is not harmful to you, balancing the profit motive with considerations regarding public health (which become more and more precise as science advances); imagine if all that was taken away - how many people would die or suffer from terrible food, even more than they do now? This is what the drug market has been like for more than 40 years. People got damaged by shit product devised by criminals to maximize their profit. And that's the WOD's fault, entirely.

Brazil alone must have had more than 150,000 deaths attributed to drug trafficking in the last 30 years.

Blaming that on the US is absurd. The US does not control Latin America. If it did, the Socialist & Communist movements that have been persistent there for so many decades would have never existed to begin with.

The premise is thus: every nation in North and South America must perfectly legalize all illegal drugs across the board for use, production and distribution (any imperfect law structures could cause illegal behavior), else the nations that do not establish perfect systems are responsible for all ills related to said non-perfect legalization no matter where they occur in the hemisphere. That's what is being proposed in concept if you extrapolate it.

I support the complete legalization of all drugs. However, trying to pin all ills on the US, is nothing more than a political convenience. It occurs with practically every bad thing on the planet. The US does not control the world; take China as one example when it comes to drugs, or broader Asia (most of which frequently shares China's general sentiment on drugs) - the US didn't impose those policies on China. The US doesn't control Latin America any more than it controls China or Asia. The same mentality that has existed in the US regarding the war on drugs, is in fact very common throughout the rest of the planet, including in Latin America.

The US is not responsable for all, but its absolutely clear that the US is willing to take diplomatic action against countries that try to change direction. This is specially true in Latin America.

The US has active military operation against drug production all over Latin America.

Plus the US is responsable for the massive demand that drives a lot of these activities.

Your are dramatically underestimating the number of deaths due to drug violence. Mexico alone accounted for over 100k as of several years ago. I suspect millions could be a bit of a reach, but it's probably within the range of reasonable estimates. I can't seem to find any good estimates.

I suggest this Kurzgesagt video:

https://www.youtube.com/watch?v=wJUXLqNHCaI

Deaths might not be in the million range, but the number of ruined life thanks to the war is well beyond millions.

http://www.drugpolicy.org/drug-war-statistics