It has never been otherwise.

I considered joining the military, but was rejected for a silly medical reason. I registered for selective service like I was supposed to do and never got drafted.

I don't feel guilty at all.

Not so. Ever heard of noblesse oblige? It used to be that if you were blessed with higher birth, breeding, and/or resources you were expected to fight. That idea extended into the 20th century. Bush Sr. and JFK volunteered. A lot of well-off, educated folks fought in the Civil War, the two World Wars, etc. Nobility were expected to put their lives on the line. War and Peace is all about that. It was that way for thousands of years. Here is a famous passage from the Iliad (Butler's translation on the Internet) that expresses this principle:

Then Sarpedon said to Glaucus son of Hippolochus,
"Glaucus, why in Lycia do we receive especial honour as
regards our place at table? Why are the
choicest portions served us and our cups kept brimming, and why
do men look up to us as though we were gods? Moreover we hold a
large estate by the banks of the river Xanthus, fair with orchard
lawns and wheat-growing land; it becomes us, therefore, to take
our stand at the head of all the Lycians and bear the brunt of
the fight, that one may say to another, 'Our princes in Lycia eat
the fat of the land and drink best of wine, but they are fine
fellows; they fight well and are ever at the front in battle.' My
good friend, if, when we were once out of this fight, we could
escape old age and death thenceforward and forever, I should
neither press forward myself nor bid you do so, but death in ten
thousand shapes hangs ever over our heads, and no man can elude
him; therefore let us go forward and either win glory for
ourselves, or yield it to another."