You may be lucky enough to have good parents and caretakers that look out for you.
Unfortunately these people may have instilled in you a sense that everyone else wasn’t
as selfish as they really are. Another factor might be that these people are older and
come from a time when people were somewhat less selfish. What you need to
understand is selflessness has bled out of the culture. There are many reasons for this
but on an individual level game theory may help us to think about it. It is based on a
rough reading of the prisoner’s dilemma.

The chart attempts to show an act and a response. If you act selfishly and the other
party responds selfishly, neither of you loses. I made up the term balanced economy for
this because this is where the concept of paying someone what they’re worth comes
from. You could use the analogy of labor unions and employers, both selfish, pitted
against each other. But out of this arrangement comes fair wages for the employee. If
you act selfishly and the other party responds selflessly, you have effectively exploited
them. An example, if you had a project and your friend did most of the work for it and
he’s sick the day of the presentation. You take all the credit for the work and when the
friend wants to hang out again you don’t return their calls and emails. Similarly when
you act selfless and the other party doesn’t, they exploit you. Lastly when both party’s
are willing to act selfless I call it reciprocity. This is different from balanced economy
because both parties are acting without compulsion.

The game theory aspect comes in when you realize that while acting selflessly is the
ideal, it only has payoff in certain contexts. As the culture moves away from selflessness,
those that still exhibit the trait suffer the most (as they are getting exploited by those
who are selfish). It might be a pragmatic to be selfless when you might be exploited
only a third of the time but once it gets above two thirds it makes less sense. So the
formerly selfless become selfish and a vicious cycle begins as people employ “defensive
selfishness” to keep from being exploited.