I think the main problem is that most smokers do not have the imagination to contemplate how it feels to be literally in pain and fighting for your breath when exposed to smoke.
None of the smokers would suffer anything like the way a smoke sensitive person suffers, if they were forced to breathe fresh air and no smoke.
Oh I know they might suffer some withdrawals from the nicotine, but that is something that could never be as painful as the way some of us suffer from passive smoke. Withdrawal from nicotine is not deadly to anyone.
Smokers need to learn to put themselves in the shoes of someone who has a really bad reaction to smoke. Some non-smokers who are tolerant of smoke and support F2C consider themselves really liberal, are actually just as bad and closed-minded as many smokers by not understanding this. This is a fake tolerance, because it does not take into account or tolerate people like me.
Think about it as a disability if you like, allowing smoking in public places discriminates and makes places inaccessible for many people, which would not be tolerated if it were something that was a more recognised disability.