Well first of all, and as much as your deep-set hatred for smoking may not let you see it, you get a MUCH different feeling from a long drag on an American Spirit than you do from smacking yourself in the head with a hammer. One can be described as quite pleasant, the other quite...blunt.
I'm not a regular smoker, but I'll take a drag from a friend's every few months, and I enjoy it. But I also lost a family member to lung cancer, so I am particularly careful.
From my own anecdotal evidence, people start smoking in three ways:
1) Started as a kid under 16. Usually through parental influence (if they're smoking around the house a lot, you become very likely to). Otherwise through peer pressure (cool kids behind the bleachers).
2) Started while drunk. See the sister-comment for details.
3) Dated a smoker. This one will get ya, and definitely was the closest I ever got to smoking regularly. Once you get used to the smell of it, the taste of it, the release of a post-coital cig... I'm sure you can imagine how it can be to be deeply in love with someone and have incredible sense-memory connections with their brand of cigarettes.
Hopefully this might give you a little more compassion for people who have become smokers through any avenue, and instead of mocking them for their choices, help them seek cessation therapy.