Humans are just evolved animals.
Whether competing for the best food, jobs, mates, or environmental niches, anything goes, and the alternative is failure and death. While the above might be a severe distortion of the Neodarwinian viewpoint, I find that many science-oriented people seem to believe it. Contemporary science is in the process of learning that this philosophy is a load of garbage. Nature doesn't work that way, and animals don't act like that. We are discovering that cooperation is one of the most powerful evolutionary forces around.