Conservation of Risk

I recently read an article about how bicycle helmets can increase the chance of having a car hit the bicyclist.

(Note that despite this wearing a helmet decreases your risk of serious injury.)

I was prompted to think of other examples of "conservation of risk", where your own efforts to decrease risk are negated by the actions of others.

An obvious example is freeway speed. It may be safest, in theory, to drive the posted speed limit on curves or in rain. But other cars normally speed, making it best to stay with the flow of traffic.

Safe internet use is another example. I would be quite sad if someone hijacked my Google account, since I have not made a local backup of my gmail in many months. But my password is quite strong: my personal risk is probably "average" through something potentially happening to Google or the LCC computer system.

(As an aside, why doesn't Google provide an automatic "clone copy" of accounts to people who use less than 40% of the potential storage space, so those whose accounts are hijacked can keep going?)

Bicycle trailers for infants are a third example. Since I never cycle on gravel or sand, I have a bicycle seat for Smiley instead of a trailer. A trailer would be safer for him if my bike did fall over, but I judge that risk smaller than a negligent driver hitting the trailer at an intersection.

What are other examples?