I like, but selfishness is not the same thing as self-interest. All actions of all humans are motivated by self-interest all of the time. It is not possible for a creature that is only capable of perceiving its own perceptions to be motivated by anything else. The question is only what each individual considers to be in its best interest, based on its own unique experience, beliefs and circumstances. Does it consider the establishment of a mutual self-interest with you to be self-advantageous, or has it determined the opposite, that it is best served by imposing its interest on yours, by being selfish? Selfishness as creed is not human nature, there are ample examples in our history of entire nations that embraced the former and flourished eg the Cathars, Arawak and San. Unfortunately they inevitably get stomped out of existence (then written out of history) by groups that have embraced the latter. Because when reason fails, violence invariably follows. Perhaps some day we will evolve past the disgusting cult of materialism to a collective understanding that being selfish is ultimately counter-productive, since it almost always necessitates others to be selfish in return, which necessitates you being more selfish, and so on until violence ensues. Perhaps its already too late. We still have a choice.