I agree. Selfishness has a horrible rep but the kind of self-ish'ness that entails looking after yourself and taking responsibility for your life without being inconsiderate and disrespectful of others, is vital. The more our own needs are met and the more self-actualized or empowered we feel, the more likely we are to better others anyway. So some selfishness is, indeed, a good thing.
I know it seems like not everyone can be happy, and that's a horrible thing, but I don't think we were born to suffer and trudge our way through life, especially if inherent circumstances don't demand it.
Be happy. Then, if you can or if it's part of you, share that happiness with the rest of the world or your world, in whatever way makes sense for you. I do believe that if you're living in a way that brings you joy (truly, not egotistical happiness) then you will probably in some real way benefit others, whether it's Mother Teresa style or not.