Heroin, spice, meth, cocaine, benzodiazepines, opiates, marijuana, and on and on.
Drugs elevate one's mood to euphoria. People like to feel euphoric.
Dependent use of drugs and substances leads to pain and suffering.
Euphoria is short lived and pain and suffering a prison which seems impossible to overcome.
It's not. Treatment helps. Treatment works. Treatment can give addicted people a new, bright life.