None of us believe that ending the Drug War will end violence altogether. It will, however, minimize the violence that now exists & GREATLY enhance freedom.
Do you think that the drug lords would just disband, quietly go get respectable jobs, and become law-abiding citizens, were drugs legalized? I suspect drugs are merely the target of opportunity, and there would just be a shift to a new lucrative, illegal, and violent line of business. I find the fight-crime-by-legalizing-whatever-criminals-do rationale a bit weak.
However, I do find merit in an honest discussion of jurisdiction (should the feds or the states decide whether to address the issue). Good luck getting the federal government to abide by anything in the Constitution these days. And, they have the interstate-trade catch-all that gives them total license.