I've just started playing Minecraft multiplayer, and I'm on a prison server that's turning out to be pretty fun. I'm trying to amass "Behavior Points" by hard labor, to eventually buy my freedom.
Each time I run from the quarry to the bank, I have to be on guard against players who stand in the path and try to kill me and take my stuff. A lot of the time they succeed, because I have neither sword nor armor and I'm not skilled in outmaneuvering them. And they're not going to stop, because it profits them more to steal than to work, and makes them feel powerful, too.
I'd wager that I've lost half again the amount of BP that I've got in the bank. So they're sapping at least a third of my hourly earnings. And I've died dozens of times so far.
Imagine if this were real life, and I didn't get to respawn after every death.
There are people in the world who want to harm others. They want to kill, to steal, to dominate. They are wolves, preying on the world's population of sheep. And the sheep are helpless against them.
But there are sheepdogs, too. These are the men and women who stand between the wolves and their prey. Just as a fireman saves people from the flames, a policeman or soldier - if filling his rightful role - defends people from those who mean them harm, enemies from without and within. And there will ALWAYS be people who mean harm against others who have done them no wrong.
I believe that national boundaries are a good thing (if one nation becomes tyrannical or corrupt, you can flee to a different nation), but this is a separate issue: Even if there are no enemies without, there will still be enemies within. And if no one steps in to stop them, the aggressors will always win.
I like what Patton said: "No poor bastard ever won a war by dying for his country. He won it by making other bastards die for their country." But really, in any major conflict there will be casualties on both sides. And if it came down to it, I'd be willing to die to defend my nephew... my parents... my town... my state... my nation. Not for the abstract, but for the people and their right to live unmolested by wolves.
It's all a matter of where you're willing to draw the line.