>Prohibition is the only reason those cartels have customers.

Well, strictly speaking, there are more elements to the causal relationship. If no one wanted to purchase drugs, this would also preclude the cartels from having customers. In this sense, irresponsible drug consumers are at fault as well. Indeed, many conscientious drug users have turned to various dark markets for "fair trade" drug suppliers.

Nobody is forcing their customers to give them money (save possibly the cartels themselves, I'm not sure). They could go with out or go to a country where it's legal, among other options.

...because that's how addictive drugs work? Drug addicts make rational choices and have lots of money to spend on planning international trips?

They had a choice the first time, at least, even if you claim it took that away after. It seems odd to blame one group of people for 3rd degree consequences when ignoring the rest.

That seems to be an unpopular statement, but it's still true.

It's like asking people to stop voting for the least-awful of the two candidates showcased on the teevee. Yes, they should just stop for their own good and for the public good, but it's not going to happen.

I'm not expecting them to stop, I'm saying they can't simply be absolved of responsibility if you're going to blame the law as well.

I think you're making a category error. What exactly are you saying the users are responsible for in the behavior of the cartels?

The blame was in a conditional statement: if you blame the law forbidding drugs, why not the people actually funding the cartels? They may not intend for such to happen, but neither could it happen without them.