AI is, in fact, an existential threat.
The issue isn't that AI is super intelligent. The issue is that AI is super dumb.
The reason it's an existential threat is that humans are dumb too, and we've been caught numerous times putting dumb AI in charge of automating very important decisions that affect life and death.
Legislators are writing laws with AI. Police are using AI to determine who to arrest. Lawyers are arguing cases with AI. Judges are basing their decisions with AI. Militaries are automatically generating and approving assassination lists with AI. And the leaders of the most powerful military in the world is now working to build autonomous weapons with AI.
Shortly after the US bombed a girl's school that was targeted with AI, the UN had a meeting to discuss how to regulate the use of AI in war. There was no discussion of banning it. Even the UN is planning to use AI in weapons of war. This is an existential threat to all life on earth.