Consider Pascal's Wager. Should you follow God? Consider the consequences. If there is no God, following him might waste some time. But if there is a God, the consequences are as stark as they could be! Heaven and hell wipe out every other consideration, no matter what (nonzero) odds you assign God's existence.
There is something wrong with this argument: the guy who set up the terms of the payoff schedule can manipulate you. A made up heaven can be as nice as you like, and a made up hell can be as nasty, as is necessary to make the reader tilt a certain way.
Of course, it's hardly just religion that does this. Authorities of every stripe do it! But most obviously, politicians, propagandists, and similar influencers do it. They talk up bogeymen to scare and manipulate people.
Now, if a bogeyman hails from your field, it is absolutely your responsibility to know about it and warn everyone. But if it's not your field, the heuristic is to... not care about the fire until you see smoke.
This seems like an entirely irrational strategy, and I agree that it is if you look narrowly at determining truth. But I think the attitude is entirely correct and functional when you take attention, effort, and adversarial behavior into account. Obviously, refusing to acknowledge potential catastrophes makes you much harder to manipulate. But there's an even more basic reason: if you educated yourself on every possible catastrophe, you would magnify their impact to the point that you never lived your life.
The heuristic being run into when you say "Aren't you worried about the AI apocalypse?" is probably easier to relate to if I say, "Aren't you worried about going to hell?" Hell sounds very bad, but then again you made the chart. There are, like, so many possible religions to think about, and someone with an apocalyptic issue wants to make it my issue every five minutes, never mind all the stuff my government wants me afraid of. Call me when you have some brimstone that I can actually smell myself.
This applies doubly when the catastrophe in question is reasoned about in a style that resembles Pascal's Wager (as is often, but not always, the case with AI Apocalypse stuff). You want something less philosophically Bayesian and more tangible - the equivalent of Germany invading Poland, so anyone can potentially see the problem is real.
Older people often spell this heuristic, "Well, if that awful thing happens, they can come get me here in the garden." Meaning, I refuse to let the bad times steal even one minute of the good ones.
The heuristic is timeless because the technique is timeless. To the political move Bogeyman, we have the counter-jitsu Refuse To Care About Bogeymen. I don't think the people pointing to non-catastrophes explicitly think of it in those terms - I think the behavior is more instinctive than that - but I think the intuition behind the argument is less "I know this potential catastrophe isn't real" and more "worrying about potential catastrophes is a costly and losing game".