Of course, not all young men, even the fanatics, become terrorists. Young men are not all the same. Different outcomes might be due to different social factors. Many terrorists come from criminal or deprived backgrounds. We know that a neglected or abusive childhood can result in antisocial or deviant behaviour later in life.
An interesting perspective on why so many young men are drawn to fanaticism and violence.
Read more here:
https://aeon.co/ideas/what-every-dictator-knows-young-men-are-natural-fanatics