It is physically impossible to be addicted to pot. The ignorance on this subject is mind-blowing.
They used to say that about cigarettes too. I don't think marijuana is anywhere near as addictive as tobacco, but clearly there are people who have a great deal of difficulty quitting marijuana, who will use it habitually when they know using it is causing them problems. Maybe it's just like Internet addiction or gambling addiction. I don't know. I tend to think though that even psychological addictions are actually physical. What goes on in your brain is not magic. It's all electrical, or chemical neurobiological function, something physical. I think there is probably less difference in what we term “physical addiction” and what we call “psychological addiction” than we think.