Selfishness is mankind's fundamental defect. At the root of every problem is selfishness. Where there is jealousy and selfishness, there is also disorder and every kind of evil. Every selfish person is potentially your enemy.
All sin is selfish.
Divine love is the opposite of selfishness. Giving is the opposite of acting selfishly. We are products of a corrupt culture that teaches selfishness, so it's not unusual for us to think it's not so bad. However, you're unable to change by yourself. You can't change the fruit without changing the root.