Some studies have found that illegal drug users earn more than average and are more productive than average. Though in searching for the relevant studies, the first thing I found was this followup:

http://onlinelibrary.wiley.com/doi/10.1111/j.1465-7287.1998....

Quote: "Using various measures of current and lifetime drug use and accounting for alcohol-use comorbidity, the authors find predominantly insignificant relationships (both direct and indirect) between drug use and both wages and absenteeism, regardless of gender."