Certainly there is a danger of any technology being used for ill purposes. Let's be honest, the human race has lived under nuclear capabilities for over 50 years and, so far, nothing. The same is true, for the most part, of chemical weapons outside a few isolated cases. AI just seems to be another technology that can have a horrific downside, if we allow it.
I admire Elon a great deal and am glad he is blowing the whistle on this because it is something we need to remember and work against. However, it is far from a certainty.