A major part of the prevention of tobacco use is education. This is partly done through explaining the health impact on the people affected by smoking (smoker+s

A major part of the prevention of tobacco use is education. This is partly done through explaining the health impact on the people affected by smoking (smoker+surrounding), partly through moralizing (since health and the personal responsibility for ones own health are exercised as a value). The latter nicely fits with an externality argument based on scarcity of resources in research & treatment. At this point, if you accept all those premises, lung cancer research for smokers is a negative externality for all the non-smokers in need for research & treatment. And it's not necessary that those premises are accepted on an individual level; it's enough to just teach them. Long term policy making is in many value questions just a proxy for mass education. You currently don't have any of that for the misuse of medicine, etc.