Why do humans like secrecy and concealment? Concealment of information, ideas, food, property. Why do humans enjoy seeing people who are less fortunate than them? In our current society everyone wants to be on top of the ladder in order to control and dominate others.
i think ppl are afraid of being on the bottom and only see the possibility of a hierarchy instead of equality, and that is why they want to be on the top. and sometimes seeing ppl less fortunate makes a person feel better about their own shitty situation. but i don't ppl are inherently evil like you seem to imply here.
I believe that people like secrecy and concealment because of evolution. Deep down, everyone wants to out-evolve everyone else, have a better life in order to increase the chance that they'll leave a strong legacy. It's a primal instinct. It sounds so much better in my head but really, I do believe evolution plays a huge part in it all.
The simple answer is: fear. We fear how fragile we are. We fear other people. We fear power. So we want that power for ourselves. And the best way to do that is to shove others down and hoard for ourselves. But I really like s0ma's answer too. Maybe not out-evolve others, but the general mentality of, "Survival of the fittest."