The interview that got John Lennon Killed - "we are run by maniacs"

Looking back at the Vietnam War and the fact that it would simply not have happened had JFK not been killed by the CIA, is it fair to wonder why a lone gunman killed John Lennon as he incessantly criticized said war?
Is there a war that America has waged that was actually justified now that we know the deep state truly controlled America since at least that time?
Was John Lennon killed by the CIA for speaking out against their war?
It's always a lone gunmen isn't it?
Is MK ultra involved?