Who benefits from it.

I doubt very much that the creators of antivirus programs, and especially their leaders and owners were interested in the extermination of all viruses.
I also doubt that the owners of pharmaceutical corporations were interested in the extermination of all diseases and epidemics..
I doubt, that the power structures are interested in the extermination of all enemies.
Indeed, in the event of the extermination of the above factors, how will they receive income and funding??