In your mind, dangers from AI are imaginary and not even projected, therefore, you don't see any reason to warn about them, because you don't think the dangers are real. You don't believe the road is actually closed up ahead, so you don't think it's necessary to post the sign.
In Scott's mind, dangers from AI are not a known fact, but are somewhere between highly probable and a near-certainty. In his mind, there are well-grounded justifications for believing that AI poses substantial future dangers to the public. Therefore he also believes he should inform people about this, and strives to convince skeptics, so that we might steer clear.
It's easy to understand why someone who believes what you believe about AI would of course not warn people about AI. It's also easy to understand why someone who believes what Scott believes about AI would want to warn people about AI. Your contention is with his confidence for being worried about AI, not his reason for wanting to warn people.
