US states literally have been built on the motto "come and take it." Americans have been the most common foreign volunteers to die in places like Ukraine and Syria.

Invading America would be like invading Afghanistan. If you wrestle a pig, expect they might even enjoy it. And yes I have fought in a civil war, I know what it's like, even without the advantage of American weapon, so no need to go down the road of me not understanding the implications. It would only embolden us, we wouldn't learn the lesson you're thinking.