What does that have to do with ordinary extremist that is cog in a machine, does no splash whatsoever and have no status whatsoever?
And yes, in societies that reward cruelty and killing, cruelty will be high and so will killings.
Convicted male mass-murderers and soldiers are not really comparable. Convicted male mass murderers were not all that succesfull in having and keeping girlfriends until caught and locked. Just about only having a lot of children were the ones that run cult too.
It's two pressures meeting at an equilibrium of ordinary extremist. The evolutionary pressure to accomplish something and the social pressure to not break any laws.
Wut? What social pressure to not break laws when we are talking about terrorists? They are under social pressure to break laws, especially when otherwise isolated from non-terrorist social contact.
Especially war killers you mention tend to typically be in group that reward killing and peer pressure each other into it.
And yes, in societies that reward cruelty and killing, cruelty will be high and so will killings.
Convicted male mass-murderers and soldiers are not really comparable. Convicted male mass murderers were not all that succesfull in having and keeping girlfriends until caught and locked. Just about only having a lot of children were the ones that run cult too.