The risk from terrorism is, most greatly, the fear of terrorism and the effort a society will expend on trying to stop future terrorism, which in itself generat

The risk from terrorism is, most greatly, the fear of terrorism and the effort a society will expend on trying to stop future terrorism, which in itself generates fear and adds to the likelihood of spending more on preventing terrorism... In short, it's all too easy to let it become a vicious cycle that simply is not justified based on the actual damage done by terrorism. To circle back to your analogy to floods – I'm not sure about what you're suggesting. Are you saying we need to look at a larger timeframe? If so, I would point out that I was considering precisely the timeframe you suggested. But, beyond that, looking over the last 100 years, SIDS and choking have certainly killed more... and I would expect they'd continue to do so over the next 100, even if the current anti-terrorism measures were never enacted.