It is just an explanation I got from net why these idiots kill others
Prophet said, 'Nobody who enters Paradise will ever like to return to this world even if he were offered everything, except the martyr who will desire to return to this world and be killed 10 times for the sake of the great honour that has been bestowed upon him'." [Sahih Muslim, chapters 781, 782, The Merit of Jihad and the Merit of Martyrdom.]
