Somebody gave one of my students a fairly (< 1yr old) new laptop the other day because they got it loaded up with viruses, (virii?) There is a market segment with more money than brains, it is large.
In Latin, "virus" is a mass noun, like "stuff", "water", or "poison", its original meaning. There is no attested plural. Being of originally Greek origin doesn't help matters.
In English, there's never a reason to use anything other than "viruses".
Actually, virus is a "mass noun" (uncountable) and has no plural. If it ever had a nominative plural it would be vira, and out of anything, viri is its genitive singular.
I don't see how (a) one example of stupidity is representative for the populace at large and (b) how this particular example is relevant at all.
If one person is ignorant in one domain, that doesn't mean that person doesn't excel in another domain. Stupidity is relative.
E.g. my father can't use a computer and thinks his computer is broken whenever he has minor problems with it. On the other hand he has a perfect track record in managing government institutions and the family's business and he's also extremely good at handling money and being a cheap bastard. He never learned to use a computer simply because he can delegate such tasks to his subordinates (or me).
And yet you've placed him in the bucket of people with more money than brains, simply because somebody on this planet sold his computer because it was virused.
http://lysy2.archives.nd.edu/cgi-bin/WORDS.EXE?virus
In English the plural is viruses.