People really miss the point about why military recruiting occurs so early at 18. The brain is not fully developed yet. At 18, people have not learned right from wrong, love, death, loss, true responsibility to someone else. Sure, someone at 18 have gone through these things and it hopefully helps guide them in life, but it may not penetrate the brain as a life lesson yet. The brain is basically a blur up until your thirties, because you don't have any of these experiences to compare to until you encounter them again.

That's why as you get older you start to understand what the heck is happening in your life, because you finally have multiple experiences to compare to. Then you can finally understand what is meant to be traumatic and what is right and wrong. The first time you went through something you were basically numb to the experience.