A burglar is one of the most dangerous people you will meet. You have no idea who they are or what they are capable of doing, but one thing is certain - they have no sense of right or wrong. The most dangerous person you will meet is someone with no shame, no conscience, no feeling of guilt, and no remorse. They will feel free to do anything they want and feel no sense of wrong-doing, including killing someone for their possessions. I automatically deduce that someone breaking into your house in the middle of the night fits into the above category. What other kind of person would do such a thing? You have to assume the worst (that they have a gun and are planning to use it) in order to protect yourself.