Keeping an "Ego" in check is still pretty experimental, not yet proven really possible!
Truth is everyone has it deep down, it doesn't show always, but once a certain button is pressed on that "said" person's life, you'll see him/her unleash the beast, for real...
Exactly, there is the big problem, that button is then pressed and very few manage to fix it and when they realize it they no longer accept even that they pressed the ego button.