As per my views it's an invisible war of world secret agencies who trained such person. A few years age I read an article on it and it was told that some agencies like MOSAD adopted infants from Muslim world and they trained them for the said purpose. They make them bomb carriers and furthermore they don't know anything about suicide. No doubt revenge is also a fact but this is impossible to produce such a heavy amount of persons. I don't know that how much reality it does have but as per me it seems sound fact

__________________
Irady jin k Pukhta houn, Nazarien jinki Khuda pr houn
Tlatum Khez mojo se wo ghabraya nehi krty