No, you see virtually no internet user can create a virus. They say they can, but they lie(most "virus makers" anyways). Virus are the result of a military cyber weapons experiment gone horribly wrong. They would do much like this idea, use networked computers etc. This was in the early 90's, dawn of the internet. One day they were working on their new weapon, taking 30 years of virus and AI experience, tests went great. Then one fateful day someone fucked up with the security protocols, and the virus jumped through computers until it eventually escaped the military network and made it to the internet. Virtually all viruses that are out here nowadays are the result of randomly made attacks by this mega virus, which stealthily lives in many machines, utilizing a fraction of their bandwidth as launch pads for attacks, yet the usage is so miniscule, the user will never be suspicious. Part of the attacks are spent spreading to new hosts, the more hosts, the more damage it can do. The virus is an AI, not a program, if it used all it's powers at full 100% capacity(like a dumb, brainless program), it would do catastrophic damage, but then it would become apparent that viruses are too much of a problem, and the internet(and clients) would be redesigned, making it mostly neutered.(some theories say that the mega virus was attacking at near full power in the mid 90's, but had taken over so few computers that it was not an issue. In the late 90's it re-compensated to save itself)
That is the virus theory.(yes this is a joke)