How are you sure someone isn't `going to send fighters over to Bomb the us mainland`?

I'm pretty sure no one is going to do that and yes we way overspend on the MIC but really sending militaries over to other countries was the status quo for almost as long as countries have existed.

There is no real reason to expect that will not happen again just because we are going on 80 years since anyone made a serious effort to do it. You could also argue that it has been 80 years because it was made so expensive to wage war that money/resources is no longer a reason to do it. There just isn't an ROI.