The Indochina Wars are not about the US initially though
that's the entire point. The wars from the Vietnamese perspective (the more relevant one) were wars of independence. Furthermore, as an example, here is a quote from a State Department official in 1945: "the setting up of an international commission [UN trusteeship until Indochina was prepared to go independent] can only lead to one result - the eventual ejection of the French from Indochina. That would be bad for the French and the West and generally bad for the Indo-Chinese themselves."
Clearly the US did not think the Vietnamese should govern themselves. The domino theory was inherently racist because it took the freedom of choice away from the Vietnamese. The Vietnamese were making the "wrong" choice so the paternalistic West needed to correct it. So America justifies killings millions of Vietnamese because a socialist government declared independence in 1945? They were putting their ideology, economic incentives, and personal beliefs above the lives and choices of the Vietnamese.