These people were fleeing a war zone where there was a transition of government. And of course there are also large numbers of people who were unhappy or afraid of the Communist. I'm not saying they are angels, I can not stand communism.

The US also directly supported this and helped many people who otherwise would have stayed. It was part of a dilibrate strategy to weaken the North.

Many of the fears people had about what the Communist government was doing were false, and the Communist government actually implemted some sensable policies.

At that point it was not clear that the North would get more support, but over the coming years it became quite clear. The South just failed as a state way more so then the North.

A bunch of poor Vietnamese were able to defeat the biggest and most powerful military in the history of earth. That's a pretty hard thing to explain.

"That's a pretty hard thing to explain." Well, the vietnamese army say that they did it by leaving 10 000 vietcong in the south after the separation and rapidly subsumed all resistance movements as front organisations under direct northern control. The south was thoroughly corrupt, brutal and inept but having another state sponsoring and controlling a guerilla war in your country could not have helped. https://www.amazon.com/Victory-Vietnam-Official-History-1954...

So, South Vietnam resistance was supported by the North. The government was supported by the most powerful military ever and a whole list of allies. But somehow they lost.

Also, lets remember that we should not take everything they say for granted.

A lot of resistance is also passive and that is effective as well.