Buying cigarettes means giving money to tobacco companies. I firmly believe these are an example of corporations bein evil - which I understand is a controversial opinion on HN.
The tactics (spread fear and misunderstanding; discredit your oponents) have been taken up by other campaign groups (eg, anti climate change groups) often using the same scientists for hire.
"Vaping" avoids most of the social stigma of smoking and if you buy carefully you avoid giving money to tobacco companies.