People are inclined to fill in the gaps of a story with negativity when they don’t have the full picture or know all the facts, and they end up with a distorted version of the truth.
The seed of doubt begins to grow into a tree of fear, and the person starts to act out on that fear. They use their half-distorted picture version of the truth to fuel their actions, which only ends up hurting themselves and other people in the end.
