It's too bad this thread has such a negative attitude. The way the OP was worded, I'd be very surprised if anyone even had the guts to respond to the question that was put forth. If you want information from someone, you don't ask them a question, then proceed to insult them for their poor choices in life. The people responding so far are just as bad for the most part.
Personally, I'd say that 10 years ago or more, those who are blaming the tobacco companies would be right. Those same companies have been severely punished for their behavior, however, and currently have their tail between their legs to the extend of funding all sorts of anti-tobacco advertising, web sites, and various other programs. These days, I'd venture to guess that those who start smoking do it out of a sense of rebellion or because they're emulating a bad example given to them by trusted adults or peers.