[I feel like I'm admitting defeat even writing this, but I want it to be clear that the below is meant to be funny. If this article seems pedantic, incorrect, gormless, or insulting, that's me attempting to be funny.]
Avatar is a new movie about a guy named Jake who gets to play the coolest video game in history. It's the kind a lot of us have dreamt about. You know, you're flying through this awesome terrain? The very first and last things you see in the movie (counting the credits) is Jake having that same dream. That's how you know it's important!
Jake has done bad things and been in bad places. He's seen action with the future-marines in future-Venezuela. He speaks knowingly of what it's like to have the blood of children on your hands. And he's been a paraplegic for a while, too. This is the future, so they could cure that, but Jake's health care doesn't cover it. You might say "But soldiers have government-provided healthcare! Letting down veterans of the future-Venezuelan conflict makes the future-eagles cry!" I'm not sure, but I think that these future-marines are either a trans-national mercenary company, or the "security arm" of a trans-national (and now trans-planetary!) minerals concern. So who knows what kind of cut-rate plan they gave him?
So anyway, Jake killed kids, and had his spine broken, and was too poor to fix it, and had to live like that for an unknown amount of time. It is safe to say that he has had more than a few nights where he wondered whether he should really be alive. But he doesn't kill himself, because he is a good marine, which is to say that he is constitutionally unsuited to make decisions for himself. Instead he suffers.