If people always beat me up and snatch my stuff the moment I am not looking, that's not very good living. Even if I am wealthy enough to hire guards, they can turn on me at any moment and get all my stuff rather than just what I am willing to pay. So we opt for a peaceful, honest society where people are not allowed to hurt each other, steal or break contracts. On the other hand, if I learn from other people and they learn for me, we all become smarter and more productive.