One of the main reasons Eliezer started LW is to increase the rationality of altruists and of people who will become altruists. In other words, of people committed to improving the world. ... If the only people whose rationality they could hope to increase through LW were completely selfish, Eliezer and Anna would probably have put a lot less time and energy into posting rationality clues on LW and a lot more into other altruistic plans.

There is an assumption embedded here which I think it is worthwhile to make explicit. This is the assumption that increasing the rationality of an altruist improves the world more than would an equivalent increase in the rationality of an egoist. (The improvement in the world is taken to be as judged by an infallible altruist.)

I am far from convinced that this assumption is valid, though I suppose that the argument could be made that an irrational altruist poses a greater danger to the world's well-being than does an irrational egoist. Though, if you focus on the relatively powerless, it is conceivable that irrationality in egoists does more harm than irrationality in altruists.

Rational altruists and rational egoists, of course, mostly adhere to social contracts and hence behave very much alike.