Because they're coming from people who are quite detached from reality in other aspects of life and they have been affiliated with people who have rug-pulled as a tactic in in the past (like Uber and Airbnb).

The concerns could be real but these AI CEOs are simply trying to capture the mindshare of the solution IMHO.

They are genuine just like hurricane warnings are genuine. But filtering out attention economy amplification layer and nonsense you land on a simple truth - no one controls weather systems yet the chimp troupe has survived them for thousands of years. The hurricane is already out of the box.

They've never told the truth before, why start now?

We don't know what they know, I'm not even sure they know what they think they know. What I know though is that they've been lying, personally and as an industry, forever. Fables like "The boy who cried wolf" are classics for a reason.