I’d rather not have an internet argument, but I’ll give you a pointer that you can use to google for more information of the issue is of actual interest to you:
Mao, Stalin and Hitler were tyrants that forced their way to leadership and killed everyone who opposed them. Kissinger was the advisor of a terrorist government that existed long before him and will continue to exist.
“just said no, and killed that person” is a naive Disney fantasy. In actual reality people that “just say no” get vanished, tortured and killed. And their neighbours suddenly turn reaaally quiet after that. However, there is always a certain joint guitl and complicity, I agree with that. And it weighs especially heavy if “the people” are very free to protest their nation’s terrorism but don’t do so.
There is a big difference between a single dictator being a plague upon the world for the 10-50 years he’s in power, and an nation with constently changing leadership being a permanent plague upon this world for 100+ years.
That’s the reason why Kissinger sticks out of the list: Mao, Stalin, Hitler, Kissinger*.