That ... doesn't seem to answer my question.

Perhaps an example is in order.

Someone lives in an area where there recently been a number of violent muggings. They are considering bringing a gun with them when they go out, in order to defend themself; they suspect they may be overestimating the danger based on news reports. So they decide to ask here if there are any relevant biases that may be coloring their judgement., and this leads into a general discussion of what chance there should be of encountering violent criminals before it becomes rational to arm yourself (and risk accidentally injuring or killing yourself or passersby.)

Does this help clarify my problem?