It is. Maybe 1 out of 100 ever gets put into harms way. Maybe 10% of those actually do any fighting.
And PS - some of the best Rangers, SEALs and Green Berets I have served with would have been in jail or dead if not for the military. The military took a chance and it paid off.
I would dispute your numbers but let's put that aside. Do you want your tank being serviced by an illiterate punk?
Every job you have in the military has the potential of getting people killed if you do it wrong.
A company clerk orders the wrong supplies and suddenly you discover the wonderful versatility of rocks. You can throw them at the enemy, boil them for soup or bang your wounded on the head with them as a painkiller.