What is the fundamental flaw in human nature? Pride or Greed?

If you are shrewd like i, you would say neither. The only flaw happens to be what makes this world around you as you know it functional, and that is being HUMAN. People tend to dwell upon the fact that one has to much pride or one is to greedy but also fail to realize thats what our pride does---mask our judgment when it comes to one having a flaw. Having the ability to feel. What causes greed? What causes pride? What causes anger? Feelings are the flaw in human nature, however we could not exist without them. There would be no will, no determination, no drive. To feel is a gift, and a curse, but something we could not exist without.