There may be published studies, but I haven't looked. But consider the Beats. Most of them were trust-fund kids. Or the people who hung around Warhole. Or the early college hippies, protected against arrest by institutional influence. Or what they used to call the jet set.

Drug use is common among wealthy kids because they're so well protected from consequences. All children like to experiment, and have fun. So why not?

I knew a guy who burned through his inheritance, and then became a heroin smuggler. He used his friends as unwitting drug mules, and kept living the high life on the profits. But then one of them got busted, and sold him out. Oops.