That is why the American founders tried to fashion a system explicitly based upon the firm recognition of the bad aspects of human nature, rather than a utopian and unrealistic denial that even good people will succumb to those instincts if they are unrestrained. Of course what we are witnessing now is that over time, greed is a powerful corrosive force that looks for every avenue to erode those systematic protections. And it has had a lot of success in eroding those restraints.
"When one thing is practiced & pursued, ignorance is abandoned, clear knowing arises, the conceit 'I am' is abandoned, latent tendencies are uprooted, fetters are abandoned. Which one thing? Mindfulness immersed in the body." -AN 1.230