Couple things at play:

WWII: the last real war when our guys were good, and fought against baddies, and a lot of us were sacrificed in the name of this righteous cause. But we saw, relatively, a ton less damage than other allied powers, so we came away with almost a god complex mentality of our troops. They made it so we had no domestic damage to our cities and land. The ones that came home were seen as heros of lore.

And this lack of damage set us up for economic growth like none had seen before. We kept up the military, and saw great advantages from it. But it came with a bit of a price...

Now, we have one of the largest and most powerful militaries in the world. A well established and maintained Military Industrial Complex. Much of our significance in the current global power stage depends on maintaining our perceived and actual military superiority over current competitive powers, and using that might to curb possible competitive powers before they can gain resources or power for themselves.

But this narrative of military domination doesn't sit well with your average Joe. It seems a bit ...erm. bad. So we've kept up the narrative of the sacrificial savior, and propped up the cultural praise with government benefits and coupons galore.

Because you can't have military dominance without a little domestic propaganda.