[lightsighter]

> Smokers and cigarette manufacturers seem to not have some negative third party by your definition

Sure they do. If rates of lung cancer go up because more people smoke, insurance rates for the populace at large will also go up, thereby driving down expendable income for many consumers and depressing economic growth. All of society is the third party when it comes to people making poor decisions about their health.

As an aside, I realize this reasoning can certainly be abused as a justification to make any number of questionable but possibly legitimate behaviors illegal, but it doesn't make it less true in specific cases.