Why do people take drugs and drink alcohol?

Modulate emotions: People may start drinking and using drugs from curiosity, and then discover that they like the effects -- at least temporarily. Could be a craving for novelty, and a way to modulate painful emotion. In some, sporadic drug and alcohol use turn into full substance abuse and/or dependence -- taking over life, endangering health, and destroying relationships, work, and hope. The shift can be quick.