People who write viruses typically... about 99% of the time, work for organized crime syndicates. Viruses are the tools they use to extort, con and rob people these days.

Extortion: Slipping a backdoor denial of service program into a "Freeware" program and infecting a few ten-thousands of machines, then picking a target and saying "If you don't pay us $$$$, we're going to shut down your internet. No?" Sends the activation command to that network of infected machines to do a DDoS attack on that site.

Con: Popup saying "OMGZ!? YOUR COMPUTER IS INFECTED WITH THESE (lists 58 official sounding viruses and throw in some spooky works like "hacker" and "child porn")!! You MUST click this link and for ONLY $50, download the program that'll fix it all!!!

Robbery: A "Browser Helper Object" that looks to see if you have "bankofamerica.com" open. If so, starts recording any keystrokes and html POST fields. Send that info back to an anonymous dead drop computer for retrieval.

It's got nothing to do with "malicious kids" these days. It's all big money.