The poor can’t afford a lot of things. Because a lot of things are priced beyond their budget. Cigarettes may just be something else that they cannot afford.
I recall hearing people bitch about the prices of cigarettes for ages now. It seems like they’ve always cost “too much.”
By my estimation, in the USA anyway, anyone who is younger than—let’s say 53 years—really should have had a clue that cigarettes were a bad, bad idea before they ever took that first puff. It was in the early '60s that the Surgeon General had those health warnings put on each pack. So, assuming that someone was, let’s say, 12 years old at the youngest when they started smoking, they’d have to be older than 53 (or let’s be generous and say age 50) to not have known before they started to smoke that is was a really bad idea.
But they chose to start the habit anyway. And now it’s too expensive. Actually, it’s been getting “too expensive” for quite a while now, and they still start to smoke anyway. Well, that’s too bad.
I don’t know, I just can’t dredge up a whole lot of sympathy for someone who knows (and has had it hammered into their heads, again and again) that something is doing them no damned good, and yet they choose to do it anyway. Hey, they can do it, it’s none of my business. And heaven knows, I fall prey to buying things that I shouldn’t afford, and I have my own share of bad habits. But these people aren’t victims because smoking is too expensive for them. Anymore than I am a victim because a yacht is too expensive for me.
As for the rest of your reasoning, I see merit in it—I don’t think we should be in the job of trying to control behavior by “punishing” them, and I think that if we’re going to have a sin tax, there are a whole helluva lot of other things that could be taxed more (fast food? Porn? Expensive clothes?) but aren’t, as far as I know, at least not on the same level as cigarettes. But I just can’t feel sorry for people who willingly become addicted to something that is “too expensive” for them, when they’ve been warned, time and again, and again, and again, that it’s no good for them, but they insist on doing it anyway. They knew before they started that it was not a good idea. Well, guess what? It’s also too expensive for them. Cry me a river.