My purely
anecdotal $0.04 (wtih inflation...)
I used to smoke pot, sometimes infrequently (5-10 times/year) and sometimes a lot (10 times/month). My use would vary in a fashion that was fairly well correlated with how bored I was.
A few years ago, I needed to get a security clearance for a job. I applied for the clearance, honestly answered all the questions they posed about my drug use, and signed the form under where it told me that I was agreeing not to break the law - i.e. not to smoke anymore. I got the clearance.
Since that day, I haven't. It's been some years now. I never had any physical symptoms. I do often suddenly stop what I'm doing, usually if I'm bored or doing something psychedelic already, like watching Yellow Submarine, and say to myself, "Damn, I wish i was high." However, I don't do it. I have sat through friends getting stoned in the same room numerous times, and had no trouble not partaking, or even leaving the room if the smoke got really thick.
What does this prove? Nothing. It's just a data point. Take it as you will. I agree that pot is not addictive but is habit-forming...but that the severity of those habits are a matter of individual personality, willpower and situation.
Damn, I wish I was high.