These people believe that, in the entire world, they alone are preserving Islam from extinction. They feel they are benefiting the world, even if they are committing random massacres. They are certainly not worried about death. Qutb gave these people a reason to yearn for death. Wisdom, piety, death and immortality are, in his vision of the world, the same. For a pious life is a life of struggle or jihad for Islam, and struggle means martyrdom. We may think: those are creepy ideas. And yes, the ideas are creepy. But there is, in Qutb's presentation, a weird allure in those ideas.
Do you know why Hitler so hated the Communists? Because the Nazis and the Communists were both trying to recruit from the same segment of society.
Do you know why Berman finds "a wierd allure" in Qutb's ideas? Perhaps its because of it's similarity in outlook to the various collectivist tyrannies who's ideologies he has accepted?