Why do some breast feeding mothers act smug and look down on women who bottle feed?!?

Most of us don't but we DO and SHOULD explain the myths about nursing when people challenge us and or make us feel dirty by expecting us to nurse at home only or sexualizing bf. Nursing is healthiest, cheapest and best for the mother's own recovery from labor so if I'm asked, I will respond with those things but I have never and would never put someone down who bottlefed.