Smart People Do Drugs

Satoshi Kanazawa, in The Scientific Fundamentalist:

Net of sex, religion, religiosity, marital status, number of children, education, earnings, depression, satisfaction with life, social class at birth, mother's education, and father's education, British children who are more intelligent before the age of 16 are more likely to consume psychoactive drugs at age 42 than less intelligent children.

Understanding the negative health implications has no bearing. Even better, Kanazawa writes that "intelligent people are often more likely to do stupid things."