because most of the people that make viruses and malware like that are, unfortunatly, super geeks who dont know how to use their talents professionally. It is fairly easy to create viruses and malware and be nearly untraceable online. and while yes, with the right resources, a person could "technically" track them down if they devoted enough time, energy, and manpower to them, but like animal pointed out, its like wack a mole, theres so many people doing it that no one has the time, resources, or manpower to track them down, and worse then that, a lot of these viruses and malware programs are self replicating, as in they can basically travel on their own from computer to computer, so even if the original culprit is caught, the virus could travel on for years afterwards without a problem.
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