Evolutionarily speaking: If cooperation did not give advantages, why the fuck did we become a social species? Going for anti-cooperative strategies only ever makes sense in zero-sum games and practically nothing in life is.
In game theory cooperation does give advantages.
Both co-op: +1/+1 Both defect: 0/0 Defect/co-op: +3/0
That’s just one interaction. When you expand the experiment, predictability becomes a positive trait and risk is avoided. So by more often choosing cooperation, you become more predictable, avoid the risk of not gaining any points through mutual defection, and more people are likely to interact with you. More interactions=higher potential for points. When you adjust the rules of the game to not define a set number of interactions with each player and you can choose the frequency of interactions with bad reputation players, cooperating is naturally selected for. Conversely, as the pool gets collectively nicer, defection will net more benefits and the pendulum will start to slowly swing the other way.
“We are a nation of many nationalities, many races, many religions-bound together by a single unity, the unity of freedom and equality. Whoever seeks to set one nationality against another, seeks to degrade all nationalities.” ~ Franklin D. Roosevelt