You're onto something there. These imbalances (rather, deviation from the average in terms of various regulatory pathways) are absolutely key to differences not only in personality but perspective, cognitive abilities, and as you mention propensity to use psychoactive substances. I've been thinking something similar for a while now, that most people with addictions to psychoactive are likely attempting to correct for something.

Not to mention, most of the illegal compounds have pharmacological activity that would be nearly impossible to get from a prescription for most people.