Smokers don’t seem to be under any illusions about whether it’s bad for them? When people have conflicting desires, I think what even counts as “self-interest” gets complicated. Often people are acting at cross-purposes to some of their desires.
Self-interest includes chemical dependence and emotional satisfaction.
The broader point is that self-interest is not purely logical because humans are not purely logical beings.
I suppose the 'self-interest' of desiring a cigarette outweighs the 'self-interest' of preserving your health.
Reminds me of debating Bentham in high school. If the feeling of self-interest of a murderer acts upon is greater than the self-interest of someone not to be murdered, etc...
Maybe the point is not to reduce judgment to one qualitative idea.