Making the use of drugs illegal has created a criminal class and increased the profits of organized crime to the point that producers and dealers of illegal drugs are able to dictate to governments.
Federal, state and local governments in the USA spend more than 8 billion USA dollars a year on the detection, repression and punishment of drug related crimes. The governments of Columbia and Bolivia are increasingly under the control of drug gangsters. Wherever drug gangs operate, corruption increases.
The consequences of making a drug illegal are that it is only available on the black market, usually adulterated, of uncertain dosage, and dangerous to consume. Using an illegal drug makes a person a criminal, but making the drug illegal does not stop him or her from using it. The substances themselves do not make people lie, cheat, steal, or prostitute themselves. Illegal drugs have much the same effect as legal ones: coffee, alcohol, tobacco and various stimulants and depressants readily available in pharmacies. The difference is legislative, not pharmacological.
The costs to society would increase if drugs were legalized, especially those like cocaine. To effect the black market, legal drugs would have to be cheaper, leading to wider use. Hospital cost would rise. The prescribed maintenance doses of heroin programme of the UK failed. Cheaper and more easily obtained cocaine would lead to heavier use and an increase in the incidents of depression, paranoia and violent psychotic behaviour.