We've been lucky in my family: several enlistees but no casualties. I think none of them saw actual combat, just training and rear-echelon stuff.
But my uncle Bob joined the Merchant Marine, because they weren't as picky about age as the Navy was, and wound up on a floating warehouse in the Philippines. He came home OK, fortunately.
Both he and my dad signed up out of WWII patriotism, and maybe partly because home life was not so good. There's never just one reason.