I, as a citizen, do vote against politicians who either publicly have those views or have voted on those lines.. But what else can I do, other than emigrate? And that takes money, an advanced degree, and lots of luck to be accepted.
I am quite sure that the cost of providing their own security is considerably more than any taxes on legitimate businesses in mexico. So it makes sense for them from a business perspective. Obviously it won't happen overnight. Some of them will adapt and work within the system, others will find that their old ways are not competitive with the legitimate businesses, who have lower overheads.
Obviously there will still be crime, and the cartels that don't adapt will find other criminal enterprises to pursue. But it's hard to see another market that will provide them with comparable income.
It was not my intent for the comment to come off as "anti-american". Just saying that mexico making this change would move the problem to the US, which would then be forced to act, hopefully by following through with a full-on legalisation of their own (not just for marijuana).
This decision is not sufficient, but if mexico completely legalised drugs, including manufacture, sale and distribution, the cartel violence in mexico would mostly stop, because they'd be legitimate businessmen who could rely on police protection.
The US wouldn't like it, but hey, that's their problem (in theory - in practice they'd make sure this never happened by meddling in foreign affairs as they always do).