With respect to "hopelessly hooked with one snort", though, I'm not sure whether there are examples of that in the addiction literature.

Well, I knew one coke addict who specifically told me that was exactly the case for her. I don't know if she was exaggerating or not. I don't have any medical references to back up the statement, though, so I will defer to the CW on that subject. My point was that there are some people who have tendencies towards either end of the spectrum, and from what I've heard, those tendencies are often genetically determined.