"There is clear evidence that hacking and malicious software are tremendously costly for businesses and home users alike. So why do people do it?
The reasons individuals engage in these activities are diverse. For example, Max Kilger from the Honeynet Project argues that the hacker community is driven by six motives: money, entertainment, ego, cause, entrance to a social group, and status.
The economic imperative is particularly strong, given the profit that can be made by hacking databases to steal credit cards and financial information. Additionally, a burgeoning market has developed around the sale of malicious software and stolen data, particularly in Eastern Europe and Russia.
Religion and nationalism also may play in computer attacks, as shown by the actions of Turkish hackers in recent years."
More:Internet Evolution - Thomas J. Holt - Hacking for God & Country