While I wrote and reread this article, I realized it leans into areas which are sensitive. But I still find it an interesting topic: selfish vs. self-interested.
Mark Foster has an interesting entry, Acting in One's Own Best Interests, which is an excerpt from his 2002 book. Essentially he suggests that the highest form of achievement comes when people act in their own best interests.
If we need our lives to be integrated, then what is the guiding principle that we should follow which will give that integrity – which will stop us being at war with ourselves?
I would suggest that it is to act always in our own best interests. This is a very difficult concept for most people to deal with.
I'll say it is difficult! Foster does a nice job of differentiating between classical "selfish" (and self-destructive) behavior and behavior that is consistent with taking care of oneself today and for the future.
The problem with acting in my own best interests (often termed "enlightened self-interest") is that I am either unwilling or unable to define what that is. Sure, society makes "selfishness" sound bad, but society doesn't provide a lot of guidance around how to act in my own best interests either. That is how a lot of religion helps society, by giving them higher purpose / higher power for this direction. (And, yes, there are many examples of religion providing the wrong direction, but lets work at the higher level.) I suspect our education system plays much of this role as well, though it often seems to come at it from the negative perspective (if you do X - or not - you will fail).
I think there is a personal conflict at play here with respect to enlightened self-interest. On one hand, enlightened self-interest suggests that people should do what is best. On the other hand, something else guides people to do whatever comes to their mind. And people frequently get stuck on the "wrong" side of this conflict, getting into deeper and deeper cycles of making those impulsive / selfish decisions (addiction is an extreme example).
Part of the solution is developing a better understanding of the problem, mostly at the personal level, though it can't hurt to see the impact on others as well. Then you have to devise a general strategy around how to break the conflict (not just shift from "selfish" to "selfless"). Then develop a plan of action to make it work. This is essentially what 12-step programs do. It's also the way Theory of Constraints literature breaks down problems: what to change, what to change to, how to cause the change.
The real goal is to make the conflict go away. Acting "selfishly" should become the same as acting with enlightened self-interest.
Foster's book excerpt contains an interesting exercise:
Ask yourself the question: ‘If I were consistently to act in my own best interests, what would I do differently?’ List as many things as you can, both large and small.