But that is not the point. Targeting civilians for political purposes is not an act of insanity, but it is an unacceptable means, no matter the ends.
(Not saying that the ends are good in this case, nor the opposite. It just really doesn't matter.)
No doubt there are other factors involved, but to deny this key enabling factor which makes suicide terrorism an eminently rational thing to do is laughable and makes you blind to an important and maybe even the most important strategy against religious terrorism: education that sheds doubt on the literal interpretation of holy books. When you have even 1% of doubt that this is what God wants you to do, you may not be so inclined to blow yourself up.
I'm fully aware that this is a very unpopular observation to make, but ask yourself not whether it would be nice if this were false, but whether it is actually true or false. Wishful thinking does not get us anywhere.
That's a caricature. A lot of the perpetrators, like in 9/11, are highly educated and even westernized people, not some backwater goat herders believing such BS.
They could be attracted to those tactics as a mean of compensating for personal issues etc (same way weirdos shoots up a school or a cinema elsewhere), but the political element is involved too.
The fundamendalist is not someone who believes naively such things (most devout village folks are peaceful and pragmatic and could not care less), but rather someone who "goes back" into believing such things (and even has self-doubt he tries to shake by action etc).
I am fully aware of this, I said so in other comment. https://news.ycombinator.com/item?id=10564189 The mistake you are making here is the idea that otherwise intelligent and educated people cannot believe crazy things. Just look at the Christian nutjobs.