"What really fascinates me is - what is driving these guys to the point where they are willing to self-sacrifice for so little payoff? Are their lives so horrible that suicide is the only way out? If so, why - and what can we do to correct that?"
You know i wanted to post an answer for you, but i cant, and no one else on this forum can post an ANSWER, they can only post their thoughts. The answer i can give you, my thoughts rather are this. Imagine you are an Iraqi, or afghanistani, your parents were raised like theirs before them, to hate the west for reasons that may now forgotten, and from the time they can teach you, you are taught "the west is bad, they want us to be like them, they want to have it worse, so they can have it better and easier, if they catch you, they will hurt you or try to make you someone else" now your mind state is this as a child " my parents are telling me the way things are, so it must be so and i shall hate the west because they are evil and want to do me harm" and you are told this every day of your life, and you will pass it on to your children because you have met no westerners yet so you know no different, and then, an invasion and press your beliefs harder, and now you know what was taught to you, and what you taught your kids is true, and instead of being caught and tortured, you will die in sacrifice to kill as many as possible, so there are that many less "evil westerners" to harm those you love and know.
What can we do? Well, we can prove to them, that we aren't evil, but how long will that take? we can help them rebuild and improve their lives, but we can only reach out to so many at one time, and we can only change so many minds and views, some will always be stuck to what they were taught and raised upon.
These are my thoughts, feel free to criticise and rip apart.