Why some of computer programmers write virus?

There are hundreds of thousands of viruses out there (if not millions) and they often designed for different objectives. Most of them fall under the following categories:

*To take control of a computer and use it for specific tasks

*To generate money

*To steal sensitive information (credit card numbers, passWords, personal details, data etc.)

*To prove a point, to prove it can be done, to prove ones skill or for revenge purposes

*To cripple a computer or network By: Tasmanian Devil & Angel