I've never met anyone, or read of anyone, who was happy to fight in WWII.  They gladly served their nation, but they derived no happiness from the fighting.  Only a foolish child who watches too many John Wayne movies would believe otherwise.
Grown-up means many things.  To most adherents to what once constituted conservative values it meant men controlled their aggressiveness, competitiveness and sex drive for the good of their family and the greater good of the community.  Sadly, many "conservatives" today worship the behavior that would have disgusted conservatives in the past.  I guess the poster adores rap stars, athletes and celebrities who give vent to their aggressiveness, competitiveness and sex drives?