Selfishness is the root of all other sins. When I am at the center of my world, I am out of place and my world is out of balance. Selfishness is a natural sin. It comes easy. Selfishness is when I pout or sulk when things don't work out my way.
All men are egocentric at the core.
The law of man's fallen nature is that he shall strive to make himself the center of the universe. We are driven to seek security by trying to reach self-sufficiency. Satan tempts us the same way today through three aspects of self-centeredness. If any man love the world, the love of the Father is not in him. For all that is in the world, the lust of the flesh, and the lust of the eyes, and the pride of life, is not of the Father, but is of the world.