Beyond what has already been said, there's another dimension to the "morality" of the war on drugs that hasn't yet been covered. Despite what any well meaning police officer may believe about the moral nature of what he or she is doing, the war on drugs was started for a very explicit reason: to infiltrate the President's enemies (President Nixon, that is, and this isn't speculation or conspiracy theory--it is well documented). There is a longer history than that that extends back to post-prohibition when the G-men all needed jobs suddenly--and that history is mostly about racism. The modern incarnation of the DEA was convened by Richard Nixon because he saw hippies and radical blacks as his natural enemies, and the thing they had in common was a penchant for weed, LSD, and heroin. Thus, the drug war. It was started on a lie, and thus has literally zero moral credence. The premises don't hold, so the conclusions can't either.

Everyone who supports the war on drugs is a stooge in Nixon dirty political game. The DEA is a great example of what is sometimes called "internal lobbying" (to distinguish it from industry lobbying). Once a government department has been created, that department has to spend a bunch of time, effort, and money to ensure that their people still have jobs. Because drugs do affect lots of people negatively, the DEA has done a splendid job ("THIS IS YOUR BRAIN ON DRUGS") of making themselves appear important enough that no Congressperson will vote to kill them. It's effective and pernicious.