The war in Vietnam was hopeless because Ho Chi Minh had the status of liberator, having fought the Japanese and beaten the French.
So no one in Vietnam was ever going to vote for anyone else, if they had the chance to vote.
So then anyone ending it sooner, saved lives.
What Fonda did was to put a human face on the war, bringing it into our living rooms on TV.
That is where people finally realized how horribly inhuman and hopeless the war was, so that Nixon could end it.
We were going to have to leave Vietnam eventually, and the Vietnamese were never going to give up.
So the sooner we left, the more lives would be saved.
Fonda got us to do that sooner than we would have otherwise.
Without Fonda, we could have killed and been killed for another extra 5 years or more.