"Are all actions in life based on interest only"?

[Anomalocaris]

In evolutionary biology there are four common types of social behavior that get studied: Altruism, selfishness, mutual benefit, and spite.

Spite occurs when an animal harms itself in order to harm others.

Evolutionarily altruism and self-harm to harm others are only subjectively different obvious outward behaviors associated with the pursuit of the same underlying survival strategy.    If the outward behaviors were detached from the underlying strategy, then tendency towards these behavior would soon be bred out of the gene pool.

The strategy is to pay an obvious upfront cost to pursue more subtle but more consequential long term benefits.     Obviously such a strategy is sophisticated, may involve multiple small or indirect profit stream, and require more work on the part of an observer to map out and weigh up the cost and benefit, then simple transactional strategy of running faster or be eaten.   

People who see ultruism or self harm in these sees the obvious upfront cost, but either neglected to see the long term profit, or neglected to tell you the long term benefit in order to tell a better, either more upbeat or more depressing, yarn.