Only a few of the south Vietnamese people did not want North Vietnam's rule because they were anti-communist. They preferred American rule in which they had scope of getting more rich than the others (as everyone is equal in a communist rule). They did not wanted to lose the special treatment they got when they did not support communism by Americans! Whereas if they chose communism they would have to deal with poverty and everyone would be equal no matter what. (also sometimes, freedom of speech, religion, etc. Is lost in communist rule)