Granted. Your life goal becomes to rule the world itself. You work to diplomatically unite the regions and countries of the world until finally, many years and very near to what you predict to be the end of your career in diplomacy, you finally succeed in your goal. The world is united in peace, militaries are abolished as war is seemingly eradicated from Earth for the first time in human history. All is not perfect, police are not evenly divided and, like any other era, not all are in favour of the latest stage of human history, but you've accomplished something no other has managed to do, uniting humans as a brotherhood of man. After 3 years of your rule, greed rears it's ugly head in humanity once again. A power-hungry man rises to power in a region already plagued by nationalism and a low police-force. They declare an uprising using old military weapons secretly stockpiled. The rebellion rises and like a wildfire gains popularity throughout parts of the world and groups that disliked the "World Nation". Poorly armed police-forces are overwhelmed and large tracts of land are gained and split up by the various factions. Finally, rebels rise in the capital and come for the man who brought the world together himself. It is too late for you to evacuate. Your World Guardsmen are defeated and overwhelmed by sheer numbers and hesitation to shoot into the crowds. As a tired old man you sit in your study by the fire having listened to reports of various cities and provinces falling around the world, watching the empire you worked so hard to build crumble around you. Now you listen to the reports of guard posts and defensive positions falling closer and closer to the room your in, and finally shouts as they clear the rooms around you. The fire dies out in front of you. The door crashes open. You're still staring at the small trails of smoke curling away from the embers as they pull the trigger. The world is plunged into the largest civil war it has ever seen. All was for naught.
I wish that there were better movies out today.