… is from page 248 of Michael Huemer’s excellent 2013 book, The Problem of Political Authority :
Today, organized criminals make their fortune selling marijuana and cocaine rather than penicillin and Prozac. The reason is that criminals have no advantages in the provision of ordinary goods and services; their only special asset is their willingness and skill in defying the law. Unlike ordinary businesspeople, criminal individuals are willing to risk imprisonment for the sake of money; they are willing to forgo all social respectability; and they are willing to engage in bribery, threats, and violence to pursue their business. These are the traits needed to supply a good that is illegal. By prohibiting certain drugs, we grant control of the recreational drug industry to people with those characteristics. If these same drugs were legalized, the criminals now making fortunes from their sale would no longer be able to do so because they would no longer have any economic advantage in that industry. This is the lesson of Capone and Prohibition.