At the risk of sounding flippant, this is true. I often sacrifice myself on suicidal runs just to help out my team. Even if I don't have the highest kill tally at the end of the round, I can at least deny a flag capture or chalk up one more kill for my team.
I, however, have a completely different psychology. I know I'm the underdog; I know I'm probably going to get killed anyway. I am never going to advance up the Halo 3 rankings, because in the political economy of Halo, I'm poor.
Specifically, I'm poor in time. The best players have dozens of free hours a week to hone their talents, and I don't have that luxury. This changes the relative meaning of death for the two of us. For me, dying will not penalize me in the way it penalizes them, because I have almost no chance of improving my state. I might as well take people down with me.
Or to put it another way: The structure of Xbox Live creates a world composed of two classes -- haves and have-nots. And, just as in the real world, some of the disgruntled have-nots are all too willing to toss their lives away -- just for the satisfaction of momentarily halting the progress of the haves. Since the game instantly resurrects me, I have no real dread of death in Halo 3.
Thompson also finds a way in which interactive worlds can communicate complicated differences in perspective (see: Virtual Guatanamo). More on that later.