Existential threat is a really hard thing to grapple with. You can't wait for real-world evidence of danger to deal with it.
If there's a possibility of an asteroid coming that will wipe out life on earth, waiting until our telescopes can see it to start taking action may not give us enough time to react. We have to plan for the theoretical possibility.
Maybe we'll never be able to create artificial superintelligence. Maybe artificial superintelligence will be much easier to align than we thing. Maybe it'll be hard, but manageable, possibly because we have more time to work on the problem than we think.
All of those are possibilities, but the fact that if you ask 100 people about it, you'll get 100 different opinions, means that we have very little idea how things will go. Given that, I don't like the approach of wing it / hope for the best. If we end up stifling AI innovation unnecessarily, that may mean that our techno-utopia is delayed for a few years, but we get there in the end. On the other hand, if we under-react and things turn out really bad, we may not get another try. Scenarios where AGI kills a billion people are really bad, but scenarios where we create it and end up permanently disempowered or dead are worse.
I wonder sometimes if people are just really dissatisfied with their lives, that they react with such vitriol to the idea of AI progress being delayed. I know we have a lot of problems, but how many of them are technological vs. having poor human institutions and incentive structures? AI probably won't help much with that.