With this reply I think you have confirmed you now understand that others in this thread really DO understand just how bad smoking can be for a persons health, and I hope, accept that some people can make an objective decision to continue to smoke even though they know just how bad it can be to your health.
I wish the pros and cons on everything in life were simple to look at and easy to decide on, but unfotunately life is not like that.
It seems simple and obvious to suggest that smoking tobacco should be illegal because it is an addictive habit which can, in many people (but not everyone) cause illness and disease, even early death.
But whilst it seems simple and totally sensible, the health argument is not big enough to change opinion in favor of a ban. That's because there are other arguments to consider in favor of smoking - and they're not only the whole debate on freedom to choose if you smoke or not, but also include strong political and economic influences for example.
Life's complicated
A good debate about these issues does help lots of us to learn about other peoples opinions and how different they can be to our own. That's why everyone tries to be mature and sensible
When you get emotional and defensive you run the risk of offending others - or being offended by others - especially if you consider them friends.
Just remember that good friends don't have to agree 100% about everything and that a balanced person can look at a totally different point of view and consider the argument from the other side even if they don't agree with it.