Crack, Cocaine, Opium, Marijuana, Heroine, etc. - Illegal Drugs have an enormous impact on society. They make addictive, shorten our live-expectancy and change the way we interact with other people.
Drugs are therefore not only a risk for ourselves but also for others. But many drugs have not always been illegal, but were a medication against many "sicknesses", like depressions or feeling tired.
Even "coke" got popular because it has extracts of the coca-leave in it. Also in our times the use of drugs is often a sign, that people have problems in their live they don't know any other way to escape than through drugs that change their recognition.