No offense to anyone, but, if you've not been through basic, boot camp or in the military (of which the first two are requirements) then, I dare say you dont have a leg to stand on in terms of deciding how it effects you or your temperament. Each person is different, and thus will react differently to it. Perhaps your friend isnt all that great at handling stress? IDK, but being a soldier is a high stress job, and its important during BCT that recruits are placed into high stress situations so that when they are actually in a war zone, they are conditioned to reacted appropriately or are weeded out so they never make it to a war zone.
But, you, as you seem willing to do in other threads (:cough: white privilege :cough

seem to blanket anyone associated with a thing based off very anecdotal evidence. Was your friend ever deployed to a war zone? Cause what your describing sounds like PTSD symptoms caused by things that happened during a deployment. That or your buddy didnt have a mentality that meshed well with the sort of discipline the military instills.
But, that doesnt mean that is indicative of everyone, or even the majority of individuals that have gone through BCT. I mean, by the descriptions I am reading here, you would expect me to come through and rip your eyes put for even thinking of debating me. Yet here am I, calm, happy, and you still have eyes...