Then that is their choice? Children play sports even though they break bones, people at desserts even though carbs and sugar are bad for you, people fly to island resorts for vacation even though it's destroying the planet.

On the scale of things causing negative externalities to society, e-cigs are not at the top of my list. Although, the smell of cigarette smoke and its effects on others's lungs is of course harmful to others, so I could get behind stricter regulations or banning of those.