Mother Theresa is a better person than me. Certainly, I could also be a better person, if I tried. I don't go around looting store fronts, but I could give more of my time and money to charitable causes. So how good of a person should I strive to be?
Consider utilitarianism, greatest good for the greatest number, its quite clear that a good utilitarian should give away most of his or her wealth. After all, there are many quite impoverished people out there and those extra dollars will bring much more happiness in the hands of the very poor. Yes, there are transaction costs, but there seems little doubt that almost everyone is at a margin, where an extra dollar given adds to aggregate happiness. Especially if the warm glow of giving adds to your personal happiness.
So the question is, am I at an optimum? Since I could be a better person and choose not to be, I can only be at an optimum if I weight myself higher than others. Of course, I do. We all do. But should we?