One thing which is missing from his rule is the cost of losing multiple things at once. For example, if I were to lose my coffee maker I could replace it easil

One thing which is missing from his rule is the cost of losing multiple things at once. For example, if I were to lose my coffee maker I could replace it easily. If I were to lose my computer, replacing it would be financially painful, but possible. If I were to lose my furniture, clothes, computers, television, cooking utensils, appliances and my coffee maker at once -- in a fire, for example -- dealing with all of that at once would be an issue. So I have home contents insurance with a fairly high excess, but I wouldn't expect to claim on it for any one item.