Someone who hid their illegal activities so well must have been a skilled liar. And skilled liars are often highly successful, but this isn't often argued as a good thing...

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."

I'm not sure whether some drugs have the effect of turning users into skilled liars or not, but that does sound like it would be yet another harmful (though logical) side-effect of prohibition.