Is because there's a conflict itself between humanity's desire to be more civilized (including more nice and caring), more intelligent, and more egalitarian, vs the primitive, the un-civilized, animalistic and survival instincts that people have in varying levels, as well as the resulting individual desires (especially among ambitious people) to be superior, rich, and the lust for power? It seems to me that civilization is a long term project of humanity that's only been going on for maybe the past 6000 years, we are a lot more civil than say the Romans were, yet we still have quite a lot of social progress to do, except for maybe parts of Europe and Japan. We always have to be struggling with the conservatives, the fearful, the jealous, the violent, the bigoted, the arrogant, the aggressive, the ignorant, the "incapable of thinking about others", the greedy, etc... that hinder social progress and the advancement of civilization, and as a result a LOT of people suffer and die, whether it is from people dying because of no healthcare in the United States, to people suffering health problems in much of the United States from fracking activities because of the greedy natural gas industry, to Iraqis and Afghanis that have been killed this past decade because of ignorance and fear, and greed among the government.
I've been trying to understand humanity for quite awhile, and I feel that this explanation is getting closer to why I feel that people are the way they are.