Because its the natural state of all life on earth. Its the condition every living thing has to struggle against. It can be fought individually, it can be fought collectively, but it still has to be fought and even then you are not guaranteed success.

Think of all the people in conflict areas who could live a decent life were they allowed to simply be in peace. Think of all the people who have lived good lives and then been displaced by horrific natural disasters. Its not an issue of economics. Its just a fact of reality.