> cede Ukraine to Russia
It's EU's problem, not the US (and I say that as an European) and the current Ukraine crisis originate from US's push of NATO eastwards, in complete violation of American engagements towards the Russians in the 90s.
> let the Kurds get slaughtered
Well, the US's involvement with the Kurds cannot really be counted as a major success…
> have Iran build a nuke
That's Israel's problem. (Even though, btw, I'd argue that it would have a stabilizing effect on the area, not the opposite). And the US army isn't actually doing anything to prevent that (nor did they prevent NK from getting it one decade earlier).
> Sure, its annoying that there's problems all around the world, but we all know that no one else is going to step up to do something about it
The US is creating a good chunk of those problems by themselves though… (Ukraine, Syria, Afghanistan, Irak) And I'm not even sure it's entirely by accident: the Defense has been needing enemies to justify its budget since at least the down of the USSR…