Why do people create computer viruses?

If you've experienced the damaging and expensive effects of a computer virus, you might wonder why anyone would create viruses in the first place. It's maddening to believe, but there are programmers who deliberately create viruses. Some are simply pranks others are seen as a creative hobby. Virus makers even spread political messages. Sometimes programmers have a more vicious intent like financial gain from identity theft, as some viruses collect private information and relay it to their creative source.