Security expert Bruce Schneier has published a terrific article about risk, and our fear of it, with a focus on the fundamental difference between human-instigated and other risks.
The article, which I have added to my list of pieces about privacy, secrecy, and surveillance, is well worth reading. Here is an excerpt:
We also expect that science and technology should be able to mitigate these risks, as they mitigate so many others. There's a fundamental problem at the intersection of these security measures with science and technology; it has to do with the types of risk they're arrayed against. Most of the risks we face in life are against nature: disease, accident, weather, random chance. As our science has improved -- medicine is the big one, but other sciences as well -- we become better at mitigating and recovering from those sorts of risks.
Security measures combat a very different sort of risk: a risk stemming from another person. People are intelligent, and they can adapt to new security measures in ways nature cannot. An earthquake isn't able to figure out how to topple structures constructed under some new and safer building code, and an automobile won't invent a new form of accident that undermines medical advances that have made existing accidents more survivable. But a terrorist will change his tactics and targets in response to new security measures. An otherwise innocent person will change his behavior in response to a police force that compels compliance at the threat of a Taser. We will all change, living in a surveillance state.
When you implement measures to mitigate the effects of the random risks of the world, you're safer as a result. When you implement measures to reduce the risks from your fellow human beings, the human beings adapt and you get less risk reduction than you'd expect -- and you also get more side effects, because we all adapt.