You cannot have non sci-fi proof of future events, it will always be unmeasurable theories.
So you can choose to wait and see, and maybe it will be too late or to hard to act when you have sufficient proof.
Or you can choose to start thinking about it now, and see what we can do to to set up safeguards. And perhaps those safeguards will be useless, perhaps not. That's called prevention.
You are not making a cohesive argument. First you were arguing that OP was essentially saying we shouldn't "give a fuck about anything." Now you're arguing that we should "start thinking about it now." Those are two completely different points.
You can do research and testing without fear mongering.
So you can choose to wait and see, and maybe it will be too late or to hard to act when you have sufficient proof.
Or you can choose to start thinking about it now, and see what we can do to to set up safeguards. And perhaps those safeguards will be useless, perhaps not. That's called prevention.