That's not me, but I can kinda relate conceptually. Constantly pumping anything into your body seems bad; to use your deadly sin adage, I'd call it gluttonous. Even a daily pot smoker, would likely not be smoking a bowl every ten minutes all day long. Sure those people exist, but they probably aren't looking down on nicotine users.
Totally I'm an advocate for 100% legalization of all drugs. Though with strong regulation for things like opiates, more as replacement harm reduction thing than it being something you can get at a liquor store (and you can probably argue similarly for alcohol looking only at a net harm + addiction lens, but that kind of proves the point in treating different drugs differently because of stigma).