Being self-interested is one thing. This is, and I would even argue should be human nature.

It the necessity to the existence of humankind, and all other life forms, too, actually. I even think it is beautiful. Refined self-interest is actually where charity and compassion come from. Selflessness, if you will, comes from a very deep appreciation for and understanding of the self.

Being willing to initiate the use of force and violate other humans is an entirely different issue, and is the real problem. In a word, the reactionary, violent religion called statism, which abandons the use of the heart and cerebral frontal cortex, and opts for fear.

What happens is that folks get too scared and, as you said, even former idealists who swore they would never change—change.