Especially from an artificial game theoretic perspective. Real life observations of human beings consistently show higher levels of cooperation than rational choice theory predicts alone. You are taking for granted the vast amount of cooperation and trust that goes into your society. It's so seamless that nobody notices it. People notice competition because it's more obvious when people are in conflict than when they are in harmony.

If you want predictions that hold in reality, you really shouldn't look at rational choice theory...

I used the modifier even, because I can trivially fabricate a game where cooperation yields a negative outcome for both (or all) players -- so I was discounting those kinds of games. Real life and games based on real life tend to be less artificial, but your point is well-taken.

Sure, if your view is that of a sociopath. Without cooperation you'd be sitting on a tree.

There'd be no society, institutions, states, healthcare, education, families and friendships without cooperation.

I think you grossly misunderstood my point.

Furthermore, entire social theories are built on the idea that selfishness is the driving force behind all human behavior. I could quote Nietzsche or Schopenhauer, but there are also contemporary examples (Dawkins and Singer, to name a few). I don't know if I agree with them or not, but there's plenty of conceptual drilling to do before dismissing them as "sociopaths."