While estimates are just that, estimates, North Vietnam suffered enormous military casualties during the Vietnam War. Estimates vary, but combining dead and missing together alone hover around a million dead, out of North Vietnamese population at the height of the war of ~20 million people. That is a staggering death toll - something like 5% of all North Vietnamese citizens were killed on or off the battlefield during the war, and this does not include wounded and civilian deaths

Yet despite suffering significantly more casualties than the South (and orders of magnitude more than the US), the Communist Party's rule in North Vietnam seemed to be unchallenged, and the senior leaders of that party and military like Le Duan and Vo Nguyen Giap remained unchallenged, despite most of the war seeing staggering losses for little gain. While in the South (and US), military and civilian leaders were constantly shuffled around or overthrown for political and military failures, the same did not happen in the North

Why was North Vietnam able to suffer such enormous military casualties over a very long war without serious political or societal upheaval, while that was not the case for the South or Americans?