Because they want to rule/own the world and live forever? Can you do that if there are states? Don't you need to live in an environment where you're not surrounded by enemies to pull that off? lol

I'm not saying they'll necessarily kill everybody, only those that are a threat. But when you have a world government that's controlled by you, inventor of the ASI and all your friends, if you can even get there without a nuclear war, won't you eventually want to replace the 8 billion biological human beings with something else?

The answer is literally in the text you quoted