The great enemy of human freedom is the Government. By taking money out of our pockets and spending it, it destroys our freedom. - Milton Friedman

The key to understanding the situation is the most elementary principle of economics: the law of demand — the higher the price of anything, the less of it people will be willing to buy. Make labor of any kind more expensive and the number of jobs of that kind will be fewer. Make carpenters more expensive, and fewer houses than otherwise will be built, and those houses that are built will tend to use materials and methods requiring less carpentry. Raise the wage of airline pilots, and air travel will become more expensive. Fewer people will fly, and there will be fewer jobs for airline pilots. Alternatively, reduce the number of carpenters or pilots, and they will command higher wages. Keep down the number of physicians, and they will be able to charge higher fees.

It does harm a great many other people, but primarily because it's prohibited. There are an enormous number of innocent victims now. You've got the people whose purses are stolen, who are bashed over the head by people trying to get enough money for their next fix. You've got the people killed in the random drug war. You've got the corruption of the legal establishment. You've got the innocent victims who are taxpayers who have to pay for more and more prisons, and more and more prisoners, and more and more police. You've got the rest of us who don't get decent law enforcement because all the law enforcement officials are busy trying to do the impossible. And, last, but not least, you've got the people of Colombia and Peru and so on. What business do we have destroying and leading to the killing of thousands of people in Colombia because we cannot enforce our own laws? If we could enforce our laws against drugs, there would be no market for these drugs.

You can rigidly enforce only those laws that most people believe to be good laws, that is, laws that proscribe actions that they would avoid even in the absence of laws.