No haas, I got exactly what you said, but you sorta missed mine. My point was in certain vocations.... (beyond driving down a highway per an old 1993 DOT report) ...where it requires your 'full' attention where lives are at risk, the narcotic effect of pot can easily result in injury or even death..including the job of plane mechanics. Smoking even a little can get people killed in those particular jobs. Now 'just driving down the highway'…heck, I'd rather ride with someone who's got a slight buzz on pot, than ride with someone who's constantly texting while driving the car! Your friend may not be in a position to do harm to himself or others (which is good), and probably doesn't smoke enough of it (I.e. 'hooked') to cause himself or anyone else harm. But I as a jet pilot could easily do so, as could someone in the medical field as Shalandai mentioned.
Not everyone will become a heavy drug user that uses it with good self-control for 'medical' reasons..I admit that. But if a person does get 'hooked', it could lead, and has led to more dangerous drugs with far worse consequences. You can't deny that. That's reality. I've seen these incidents for myself in both my personal life, as well as my 'professional' life in law enforcement working drug cases. Remember, I wasn't always a pilot.