Exactly. You said nothing about being invaded because it's pretty unlikely that most countries face the likelihood of being invaded by anyone, whether or not the US squanders hundreds of billions of dollars every year on our military.
And even if there was a risk to all these countries getting invaded by this unidentified invader, but they're only keeping a small military because we have a big one, then maybe if we shrunk our military and used our money on more worthwhile things all these other countries at risk of being invaded would then spend their own money on their militaries. Sort of the "why buy the cow if you can get the milk for free" concept.