From virtually the moment of partition, unifying Vietnam/conquering the Republic of South Vietnam was paramount to all other considerations, even if it took decades, even if the DRV leadership never lived to see it, even if 10% of their population was killed in the process. There seems never to have been a thought for pausing the war or postponing the goal of reunification to focus on domestic life in the DRV. Is it as simple as this: they had a nationalist, collective, and longer-reaching outlook that is tough to understand in the West?
My friend pointed out that I'm a Civil War historian and that this is similar to the Union invading the CSA. But they're not similar and that's what gives rise to my question: Support for the war waned considerably in the Union states, peace Democrats had notable victories, and Lincoln had a tight race for re-election against a peace candidate which could well have gone differently absent concrete signs of progress. It's less than four years of actual fighting from Bull Run to Appomattox. The CSA could do little to bring the fight to the Union (Unless you lived in Maryland and Pennsylvania, and only then briefly and with disastrous results). Compare that to relentless US bombing of the DRV. Union war deaths are estimated at 365,000, while DRV+VC deaths at 1.1 million (from what I can quickly find online, the Union was more populous than the DRV at the start of the Vietnam war and less populous by the end).
I think you should compare the Vietnam war not with the US civil war but with the US independence wars (or any other country's independence war).
Prior to US intervention, Vietnamese were fighting an indepenence war against France.
Making a broad list of events:
Indochina (French colony in today's Vietnam) at the beginning of the XX century was experiencing troubles and revolution movements as any other colony was at that time.
In 1940 the Japanese Empire took many cities and positions in the country, showing the inability of France to defend the country (via diplomacy or arms). Irregular local forces were formed to fight the japanese invaders
In 1944, while the local forces were still fighting the japanese in the north of the country, the french started taking territory back. When the japanese were finally defeated, these local forces turned to fight the french again.
In 1954 the french are finally defeated and Ho chi minh is declared president. It was planned to have elections in the country, but as Ho chi minh was the likely winner, the CIA backed a military coup in the south. (The exterior policy of the US seems to be: you are free to choose as long as you choose what I want).
So, going back to the US example, let's make the following made up scenario:
The US fights the english and somehow win without the help from the french. Right after the war is over there are going to be elections and Washington is likely to be the winner (with around an 80% of the votes). So then comes France and as they don't like it, so they support a coup that prevents the national elections and splits the country. I guess that most of americans would endure hardships and war to follow their national hero against a new colonizer. Something like this happened in Vietnam.