I've never been a smoker and everything sanswork has said, I could have written myself.
I don't care if people smoke, I just don't want to smell it, and I don't want to inhale it. I would not have any problem with people injecting or eating nicotene as much as they want. I just don't want to be forced to inhale it against my will.
And besides the horrible health effects, it smells worse than anything else. Yes, I can smell that you had one before you got on the bus, the stench is overpowering. And yes I can smell you smoking literally 75m away. It's totally gross.
All the strawman arguments about vehicle exhaust gas are irrelevant because at the end of the day smoking has no other utility. Society accepts (a regulated amount of) exhaust gases because we need transport and we can't make a car that does not make emissions currently. If we could make a car that did not cause emissions, it would almost immediately be illegal to make a car that did emit exhaust, and with good reason.
Like sanswork said, at the end of the day smokers are just super selfish and blame others for being "too sensitive" because they are too lazy to change their inconsiderate behaviour.
There are plenty of places you can smoke, those places just aren't conveniently amongst the general population anymore, 90% of whom do not, and don't want to smoke.
Anyone who smokes while walking down the public footpath is selfish and inconsiderate, and anyone who throws their butt on the ground is selfish and inconsiderate.
The "4m from any entrance" and whatever laws are the bare minimum required by law. Nobody likes your addiction. Enjoy the hell out of your cigarettes but please keep your shameful habit to yourself, far away from all the people who don't want to inhale it or smell it.