Selfishness is ultimately self-destructive. It's in the Bible, Mark 8:36-37, TLB. "And how does a man benefit if he gains the whole world and loses his soul in the process? For is anything worth more than his soul?"
Selfishness is at the heart of most problems between people. It's in the Bible, James 4:3, TLB. "And even when you do ask you don't get it because your whole aim is wrong—you want only what will give you pleasure."
There is a remedy for selfishness. It's in the Bible, Galatians 2:20, NIV. "I have been crucified with Christ and I no longer live but Christ lives in me. The life I live in the body, I live by faith in the Son of God, who loved me and gave Himself for me."