That fellow that knocked on our door and asked for someone that we never heard of can be pushed off as a simple case of having the wrong house, but in reality could be an attempt to see if we are home. Criminals take advantage of our better acts and deeds. Most people that carry weapons or are wise on self-defense methods are a little more street smart than the average public. You don't hear of many pro-football players getting mugged. The thugs seek out women, seniors, and the infirm.
Drunks are a prime target, and often police decoy units use the facade of a drunk for decoy attacks.
And they seldom fail to find a willing participant. The criminal finds a house without an alarm system, finds a car with doors unlocked, and waits for us to make some simple errors like walking away from an ATM machine counting out cash with the card in our hand. The criminals count on us having a delay in spotting trouble. Once they decide to attack it is fast and furious. Frequently they have little thought for serious bodily harm or even death to us.