Being worried is different from it actually happening though. If we started executing 10% of the population each year, I think more than 10% of the people would be worried they're next.

At a random 10% everyone could and should be worried that they'd be in the next 10%. That's 10% chance of being executed per year! That's really bad!

It's not at all similar to a _rare_ phenomenon, or at least it _shouldn't_ be, but some people are inclined to treat very fringe risks (or at least some very fringe risks; there are likely more people worried about being killed by terrorism than food poisoning, say) as very great risks.

That's a pretty... strange example? 10% is fairly large odds that you'll be in the next batch, certainly high enough to cause worry. I would quite rationally shy away from any activity that gave me a 10% chance of death doing it.

The idea that 35+% of people are worried that they'll be the victim of terrorism is something that we should be worried about (heh). It suggests that people's risk assessment is completely unrelated to reality. I am as close to 0% worried as I could be that I'll be a victim of terrorism. Thinking otherwise is laughable. There are plenty of actually real things to be worried about...