I think if you are going to seriously argue that the US net benefited from the Vietnam war... or that Vietnam itself would not have been better off if it wasn't attacked by the US, I just don't know what to say.
Vietnam wasn't attacked by the US, at a minimum because Vietnam wasn't one country at the time of the war, leaving aside the question of which of the Vietnams (along with the corresponding superpower puppetmaster and allies) was the aggressor.