I suspect we'll find that some smokers (in addition to being addicted) were self-medicating.

Not sure about earlier, but during WWI cigarettes were smoked at incredible scale, to help deal with the stresses and horrors of war. Ensuring an ample supply to front-line troops was major gov't priority.

And I certainly have known cigarette smokers who explained "yes, I know they cause cancer and other bad stuff - but they also help with other serious (physical and mental) problems that I have, and I'm choosing quality of life over quantity".