What is it: You’re the guy (or gal) who saves the world (galaxy, reality, whatever) all by yourself. It doesn’t matter if you came from humble beginnings or if you’re a grizzled war hero; you are humanity's one and only hope, and the only person with the skills to stop whatever impending doom is coming to your home. Sure, it would make more logical sense that mankind's military leaders would put their effort into the abilities of their vast armies, but whatever. They'll let you take the glory instead, thank you very much.
Why we love it: We want our enemies to be at our mercy. Sure, running into battle with a squad of battle-hardened soldiers is pretty cool, but watching some no-named soldier gun down a vicious alien parasite is far less enjoyable than doing it yourself. Those NPC noobs always get in the way of our carefully planned battle tactics and step in our line of fire way too often. Plus, we're suckers for the, "I'm better off on my own" and "They'll only slow me down" lines.