I didn't say that "the only reason anyone cares about existential risk is signalling". I was mostly trying to offer an explanation for the observed fact that relatively few give the matter much thought.

I was raising the issue of whether typical humans behave better or worse - if they become convinced that THE END IS NIGH. I don't know the answer to that. I don't know of much evidence on the topic. Is there any evidence that proclaiming the END OF THE WORLD is at hand has a net positive effect? If not, then why are some so keen to do it - if not for signalling and marketing purposes?