Pride is the source of all sin, and pride and selfishness go hand-in-hand.
Selfishness is a tool, pride is tool. Like a gun. You wnat to outlaw guns because they can be misused?
Money is a great tool.
We all see a number of grand scale “sin” based on unselfishness in progress. Socialism. Marxism. Wife swapping, public tolerance and even celebration of immorality.
In all of these the desire is to be “unselfish”.