They arise because there will always be a small percentage of humans who are sociopaths. Simplified, this means they are willing to harm others, not just because they are starving and NEED to harm someone to get their basic needs met (which I'd argue most people are capable of), but even to take things they don't actually need. Since most people are not willing to hurt others to take things they don't actually need (usually even willing to bend rather than fight), sociopaths have a leg up on the rest of us. They were able to rise to power way back when the first cities were being built, and have maintained a sociopathic society ever since. Sociopathic tendencies are lauded amongst the corporate elites, and without them it is unlikely one will make it in the corporate world.