I think there are two valid existential concerns regarding AI:

1) Widespread use of advanced AI in robotics/production has the ability to bankrupt the working populace, at which point something closer to pure socialism may take over; not so much an annihilation scenario.

2) AI is weaponizable -- at a certain point, given other technological advances in addition to AI, a relatively small amount of like-minded people will be able to produce unique weapons of mass destruction.