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.
To avoid having to endure the consequences of your own actions. For people with nothing to lose, suicide attacks are actually the most risk-averse choice: regardless of the possible existence of an afterworld, you're certain to escape punishment in this world. Look at Columbine-style attacks - no religion there, just semi-rational choices.
People don't blow themselves up because a book or a preacher tells them so; they do it because they are fed up with living shitty lives (either in material or spiritual terms). That is what education should bring them: the consciousness that there is always something worth living for. At that point, whether god exists or not, it doesn't matter.
These usually get planned well in advance by some very sick people who are trying to kill as many people as they can and go out in a blaze of glory. Sure, the existence of opportunistic terrorists networks that get these people to coordinate their attacks and stamp a ideology on them tends to mean that the one day body count is higher for a particular incident. Still, the body count per attacker is often comparable, it's just that the attacks happen on the same day instead of a few weeks apart.
But yeah, if we ignore the non-Muslims who do things like this we can say it's all the fault of Muslims.
Still, people don't find it inappropriate to bring up Columbine when they talk about VTech or Aurora. When people try very hard to exclude all the other mass attacks and single out only the ones connected to Islam in situations like this speaks more to their personal biases than anything else.