On the other hand, look at Korea. In hindsight it seems pretty clear that it was a huge loss to humanity that the US didn't push further north.
And of course, look at Afghanistan today.
And of course, look at Afghanistan today.
That's why China intervened?
I am not sure what exactly you are suggesting here, but its hard to believe that a nuclear war against china (and likely the USSR) in 1951 as MacArthur seemed to believe was necessary to recover North Korea would have been a net positive.
But the corruption just made a joke of everything, and of course it all ended badly. :(