Third Reason
The last group of people who hurt animals are the worst. These are people who intentionally hurt animals because they enjoy hurting things, or because it makes them feel powerful. Many of these people would hurt other people if they could get away with it. They just choose to hurt animals because animals are more helpless than people.
Why do these people hurt animals? There are different reasons. A lot of these people want to have control over others. They will hurt an animal because they think this means they control the animal. Or they may hurt the animal to control another person. For example, a husband might hurt the family's pet to show his wife what he could do to her if she doesn't obey his commands. Someone else might make his dog kill other dogs because he thinks that makes him powerful.
Others simply enjoy pain and violence. Those who enjoy violence might also destroy inanimate objects as well as animals and people.
All of the people in this last group suffer from serious, psychological problems that will probably not go away on their own. They often need the help of licensed professionals—like a psychologist. We are not 100% sure why people become like this—most are probably born with their problems, but others can get their problems from brain damage, poisonous environments, or by being treated badly themselves. Without help, the psychological problems these people have can haunt them for their whole lives.
If you know anyone who you think may be like this, don't approach them yourself. Talk to a trusted adult, and let the adult find someone to help these people.