It is a balance. And yes, social cooperation is ALSO a survival tool and a tool to gain social status, and therefore increase the odds of ones DNA being passed on.
The most effective people in terms of passing on their genes are going to be those who know how to BALANCE things.
It's better to be a dangerous monster who chooses to be peaceful than an individual not CAPABLE of being dangerous.
A monster who chooses to be peaceful is a good person.
A person who is peaceful because they are INCAPABLE of being dangerous isn't good. They are merely helpless.