Military...

I don't understand it
like At All
why someone would join.
I know people in the military and people joining and wanting to join
and i don't understand it.
I mean if you're happy with your life
and you aren't craving for a change of scenery and have no other way of leaving
then Why?
and guys that have girlfriends and are so happy with them
why are you leaving for god knows how long?
not understanding this logic
one bit.
UGH.