In my opinion, it is fanaticism taken to the extreme.
Let's face the gentler aspects first; patriotism, for one, as been regarded as a positive thing. However, even as such, it has a darker side, that is, it undermines world peace/unity for the sake of a nation's progress.
Taken to the extreme, we can have various reasons for suicide bombing. Ranging from the relatively tame and simple psychological disorders to war stratagems to a "worthy" cause. (I do not mean to insult those who plan on suicide bombing by putting quotes in "worthy"; it's just that what's worthy to one may be foolish to another. It's a relativity thing) Ultimately, though, I guess the point of suicide bombing is gaining attention and getting a message across.
The 9-11 bombing, for one, must've been a message that says, "There is a grave threat to America and this threat is real. Take this threat seriously and be not complacent nor rest on your laurels."
There has been, recently in our country, a hostage crisis. Unlike suicide bombing, there were no casualties. Au contraire, the entire shindig ended peacefully. The hostage-taker used the attention he got to expose corruption in his home province along with outlining other ills that plague our beloved nation. After he had said his piece, he peacefully surrendered. Now, what's sad is that the media and, in general, everybody, focused on the crime of hostage-taking. People were taking action like filing suits against him, psychiatrists were "mending" the minds of the "traumatized" children (who left the place smiling and rallied for the hostage-taker's release days after) but nobody even paid attention to the things he brought to light, namely, corruption and scandal.
I suppose, then, that the bitterest thing that could happen to suicide bombing is people ignoring the message and focusing on the wrong and obscenely superficial things. It means, in all angles, a life wasted on absolutely nothing.
P.S. I don't support non-war suicide bombing that involves collateral damage (i.e. loss of innocent lives). If it were just a plane slamming into a vast desert, a polar icecap or Mount Rushmore then I wouldn't mind at all