We sometimes have a sense that life is harsh and unfair. For the most part, we can deal with that. What’s more difficult though, is when we treat each other harshly or unfairly. Life is challenging enough already, but it’s worse when we cheat one another.
Being fair with one another helps us overcome the sense of unfairness that seems inherent in the natural world. Cooperation helps make life better.
When people are out for themselves at the expense of others, they’re actually contributing to the sense of harshness and unfairness that they themselves despise.