I think that the question is not thoroughly set from the start. It is not whether AI could prove dangerous for a possible extinction of the humanity, but how much more risk does the artificial intelligence ADDS to the current risk of extinction of the humanity as it is without a cleverest AI. In this case the answers might be different. Of course it is a very difficult question to answer and in any case, it does not reduce the significance of the original question, since we talk about a situation totally human-made -and preventable as such.
I think that the question is not thoroughly set from the start. It is not whether AI could prove dangerous for a possible extinction of the humanity, but how much more risk does the artificial intelligence ADDS to the current risk of extinction of the humanity as it is without a cleverest AI. In this case the answers might be different. Of course it is a very difficult question to answer and in any case, it does not reduce the significance of the original question, since we talk about a situation totally human-made -and preventable as such.