I do support what used to be called sin taxes on cancer causing activity(like smoking). I do not see it as my duty to enforce on others what I see as sin or not, so it is not a sin tax as far as I am concerned. It is to reimburse society for social costs, and to try to convince people not to make those social costs. If you are willing to pay $5 a pack for cigarettes, and are stupid enough to do so, I say fine, and move on.
I still think we should try to save you from the lung cancer that follows.
If you are late to work, and feeling tense because of that, can you murder someone? If a brain tumor is giving you a slight headache, can you murder someone? If a brain tumor is flooding your body with more adrenaline than any soldier has ever felt meaning you can no longer tell the difference between reality and fantasy...
It is a subjective gradient. Not the answer you want, but the best we have.