Why would they blow themselves up if they're armed and trained to "kill Nukhbahs"
Because they're the ultimate 'smart bomb' and used to not only inflict physical damage, but emotional.
They're also cheap.....
Such are the weapons of war in Israel today: nuts and bolts, screws and ball bearings, any metal shards or odd bits of broken machinery that can be packed together with homemade explosive and then strapped to the body of a terrorist dispatched to any place where people gather—bus, train, restaurant, café, supermarket, shopping mall, street corner, promenade.
These attacks probably cost no more than $150 to mount, and they need no escape plan—often the most difficult aspect of a terrorist operation. And they are reliably deadly. According to data from the Rand Corporation's chronology of international terrorism incidents, suicide attacks on average kill four times as many people as other terrorist acts. Perhaps it is not surprising, then, that this means of terror has become increasingly popular. The tactic first emerged in Lebanon, in 1983; a decade later it came to Israel, and it has been a regular security problem ever since. Fully two thirds of all such incidents in Israel have occurred in the past two and a half years—that is, since the start of the second intifada, in September of 2000. Indeed, suicide bombers are responsible for almost half of the approximately 750 deaths in terrorist attacks since then.
And just so you know, I'm criticizing terrorists and their adherents/supporters.