Both forces are necessary and are results of the natural course of evolution over the years. Sometimes, though, competition can also increase the chance of survival for a group. A typical example would be two male deer competing for a herd of female deer. In the end, only the stronger male deer has the chance of mating therefore their offspring will have a better chance of survival. In common words, the goal of human existence is to scramble for power and wealth.
Human society is just a stage for race, or competition.
To the losers, competition is very cruel. Competition causes a lot of stress, so not everyone likes competition. If you give up, others, including your parents, will look down on you, and tell you that you are useless. So, every one of us born in this society is forced to take part in the competition. Because human beings have needs.