If we assume that the universe is really a big dream, it is but a small step to assume that everything that happens, occurs because someone imagines it to be so. From there, it is quite easy to imagine that individuals such as ourselves can influence the world by magical power of will. Groups such as Scientology and "What the Bleep..." are fairly vocal in pushing this idea. Likewise religions believe that events can be influenced by appeals to supernatural powers. But even if things like will-power or prayer have power, we should not forget that in times of war both sides usually pray for victory and there is usually only one winner.
Whether we are simply thinking through a problem and comparing competing ideas or vast armies set out to war to fight over resources situations occur involving conflict and competition. The fittest (ideas or armies) survive while the unfit are left behind, leading to the evolution of ever fitter elements and more developed ecologies.