I think much of what the military does, training and otherwise, has a lot to do with teaching and testing the individuals adaptability.
Life can throw you all manner of circumstances, how well you adapt is critical to your survival first and success second.
Looking to the animal world, (us included) those who adapted to a changing world, both local and global, lived to procreate, others are now fossils.
Play the hand you're dealt, don't waste time bitching about it.
I was in the Navy 8 years 3 months and 5 days. Of course some of it sucked, but I'd do it again, tomorrow, if I could.