The strongest opponents of drug legalization are the wealthy big-time pushers and organized crime lords themselves. It is in their economic self-interest to keep drugs illegal, so that they can be unregulated and untaxed. Sacrificing lower-level pushers and an occasional shipment is a cost of business to them that is far less than the costs of legalization - you don't mind losing 10 million in street value in a bust if it only cost you 50K to produce the drugs. Terrorist groups that rely on drug money to survive would be particularly annoyed if drugs were legal and under government control.

So, if you support keeping drugs illegal, you are unwittingly supporting drug lords and terrorists - there is simply no way around this besides closing your eyes to the truth.

Less than 2% of people who DON'T use drugs say that it is because they are illegal. (I happen to be one of those rare folks - I might try them if they were legal. As it is, alcohol is plenty for me, although virtually everyone I know, saint or sinner, has tried drugs at some time - except for me.) The rest view it as an ethical or health issue; these feelings would not change with legalization.

Among the costs of having drugs be illegal is abuse of police power. In Dallas, there is a huge, ongoing scandal involving the police planting powered sheetrock (gypsum) on suspects and then convicting them of possession. A number of these convicts remain in jail because prosecutors are resisting releasing the details of who they are. I have buddies who are Dallas cops and they hang their heads in shame when the issue comes up.