One aspect to the "instantly hook a user" theory that I have not seen mentioned here is the following: Taking a potent drug like heroine or cocaine for the fir

One aspect to the "instantly hook a user" theory that I have not seen mentioned here is the following: Taking a potent drug like heroine or cocaine for the first time is described by some users as "pushing open a door to a very enjoyable place you did not know existed". Once this door is open, you will always know that this place exists, you can not "unknow" the experience. While some people might be able to handle the knowledge of this enjoyable place and are able to choose when and if to go back, some might not be able to. Therefore I believe it makes sense to tell people not to open the door at all. I also can imagine that the first time with these potent drugs is a positive experience for many, unlike the first cigarette or the first beer a person ever tries. The second cigarette is not smoked because the first was so good.