Hmm... I do think it is possible, albeit very rare. On the other hand, I also think selfishness isn't automatically bad, especially this sort. Typically, though, I only hear that kind of argument from someone who's been confronted on doing something terribly selfish and want to squeak out of it.
Selfishness, though, used to be a survival technique in the wild. Do what you've got to do to survive FIRST, then see to others. I guess it's selfish to, you know, eat and breathe and stuff, but that guy's definition. Still, things ~HAVE~ changed in the world, too. There's not enough sustainable biosphere on the planet to perpetually support 7 billion people; under relatively-selfabsorbed-american standards of consumption, for example, it would take 4.5 earths to sustain the current population. Even ignoring resource strain, civilization itself begins to crack and fracture in the face of incessant and indulgent selfishness. Such things are inherently uncivilized.
Everyone should, and to a certain degree, must be selfish. This can still be done, however, with consideration made for its impact on (or benefit for) others... and therefore should be. We won't survive otherwise.