Well, the problem with this argument is that is cannot really be falsified. Even if I had extensive statistical material about people smoking more than 4 cigarettes and still largely not being regular smokers after many years (which I don't), you could simply assert that it might take a little longer, citing your example of the lady that started with 27 as anecdotical evidence.
There are people I got to know as social smokers that eventually took up the daily habit. But the number was way below 85%. Maybe a 30% conversion rate from social to regular.
I myself have smoked well over a hundred cigarettes so far, and even though I do still indulge from time to time, it's not the nicotine driving me but the context I associate with the act of smoking. As Vesperae said, it's about identity, about tapping into one's dark side.
Additionally, I've watched a good number of people try to quit smoking, and the successful ones were almost always those that had no identity-establishing relationship with smoking or that wanted to shed the identity established by their habit. Those still involved in cliques or personality developments favorable to smoking seldom quit, even if their consumption was much lower and smoking history was much shorter than those of successful "quitters".
It's really not that much about the nicotine, I think.