I think we underestimate the intoxicating lure of human complacency at our own peril. If I think there's a 90% chance that AI will kill me in the next 20 years, maybe I'd be doing this. Of course, there is a knowing perception that appearing too unhinged can be detrimental to the cause, eg. actually instigating terrorist attacks against AI research labs may backfire.
But if I only think there's a 25% chance? Ehh. My life will be less-stressed if I don't think about it too much, and just go on as normal. I'm going to die eventually anyways, if it's part of a singularity event then I imagine it will be quick and not too painful.
Of course, if the 25% estimate were accurate, then it's by far the most important policy issue of the current day.
Also of course there are collective action problems. If I think there's a 90% chance AI will kill me, then do I really think I can bring that down appreciably? Probably not. I could probably still have a bigger positive impact on my life expectancy by say dieting better. And let's see how good humans are at that..