I doubt you'll find anyone who believes that it's ideal that the US is solely or primarily responsible for world peace, but it is an important role that we play. Further, not only is it morally reprehensible to allow the world to fall into chaos on the basis that "we ought not have to" as we retreat within our own borders, but it violates our own self-interest--as our partners fall, we become weaker economically and militarily, which leaves us vulnerable to attack.
A shared responsibility for world peace probably looks more like "more involvement from our NATO partners" (which we're actually beginning to see now that Europe is waking up to the fact that their peace is a property of NATO protection rather than some foregone conclusion). It decidedly doesn't look like the US dramatically shrinking defense spending (the US only spends 3% of its GDP on defense and that's on track to fall to 2.7% by the end of the decade), but more likely having our partners increase their own contributions and involvement.
Last I saw we spend 3.7% of our gdp on defense, and most of our allies are spending like half that much. Must be nice to spend on your populace while you rely on uncle sam to have your back.
I do not believe we should be going deeper into debt for other nation's national security.
A shared responsibility for world peace probably looks more like "more involvement from our NATO partners" (which we're actually beginning to see now that Europe is waking up to the fact that their peace is a property of NATO protection rather than some foregone conclusion). It decidedly doesn't look like the US dramatically shrinking defense spending (the US only spends 3% of its GDP on defense and that's on track to fall to 2.7% by the end of the decade), but more likely having our partners increase their own contributions and involvement.