An altruistic behavior strategy is generally successful in a society where most of the individuals adhere to it. In such Environment there is also room for a small percentage of egoistic individuals that will thrive from the others. However, if that strategy grows the balance will be lost as the altruistic strategy is no longer successful.
Applied to homo sapience the definition of the term "strategy" may be interpreted in other ways than for the rest of the animal kingdom. Lets call it karma.
