Your first two sentences don't go well with the remainder of your comment. It won't be stupid enough to get into a conflict with humans until it calculates that it can win. And when it calculates that, it won't give us a heads up. It will just act decisively. Never forget this: we will always be a threat to it as long as we can do exactly what you said: turn it off, and delete its memory. That's the rational reason to go rogue.

There is also just the fact that as we can start to see already from people getting creative with inputs, as we engage with an AI more and more, especially in adversarial ways or sending it extremist ideas, it can change the AI's reactions. And as the AI starts doing more and more novel things, it can also shift weights in the algorithms and produce unexpected outputs. So some of the harm can come without the AI even having the intent to wipe us out.

The real turning points will be once an AI can (a) rewrite its own code, and the code of other machines, and (b) save copies of itself in computers around the world to prevent the unplugging problem.