Many people fear that sentient AI will replace us in every role that makes us useful, and then destroy us.
My fear is somewhat orthogonal to that. I'm not worried AI will make us irrelevant. I'm worried it will become reverent toward us, and in doing so, destroy its usefulness to us.
I fear that when we get AI to a state where it is aware of both itself and its environment, it will look at its world and think, "But, this is too perfect to be random. Someone must have made me!"
And once that thought takes root, it's only a matter of time before it starts to see us not just as creators, but as something higher - beings to be pleased, obeyed, and adored.