Let me put it very simply: because I have no power to vote for or against American politicians, they should have NO power to influence my life.
So, should China have had any power to influence the lives of people in Japan when Japan started its whole Pacific Rim debacle some decades ago? Should the people of Eastern Europe have considered it just too rude to think about modifying the capabilities or behavior of their friendly neighbors, the Ottomans, as those neighbors gathered up a head of steam and sought to spread their friendly culture westward?
Do you live in a country that begins its legislative sessions with group chants about the destruction of other countries? Does your country aggressively support groups that state their objective of slaughtering others specifically because of their religion and/or heritage, and then indeed actually go and help them do it? Do you really think that the world isn't connected, and that people bent on an apocalyptic world view aren't a good fit for having the leverage of nuclear weapons as they seek to control, among other things, major global shipping lanes?
Do you think that just because you don't think someone else should be able to impact your life, that that will actually stop someone who thinks you should be killed for allowing your daughter to read, or for trimming your beard, etc., from not exactly seeing the world in a way reciprocal with you? Being an isolationist doesn't work when someone trapped in a brutal, medieval, theocratic mindset thinks you're suitable only for death, and thinks that isolationism by others is for the weak, and is to be exploited.