As seems to be typical for you, your comments are less than helpful to anyone and are just showing a personal position that doesn't completely resonate with today's internet threats. It isn't about a 'virus' for a Mac, although those are coming, at least according to the 'experts' that track these things, it is about all the other junk out there in the form of malware and other social attacks.
All Mac users aren't as sophisticated and worldly as you position youself to be, and your seeming opinion that the Mac is somehow pure and clean and not susceptable to the icky stuff out there is just a bit out of date.
You do understand that these 'commercial' anti-virus companies spend a TON of money on the front lines trapping and identifying these new threats and keeping their products up to date. Is it just that you don't like the idea of a company offering a service and making a profit in doing it or that you are just so hard core that you refuse to believe that your pristine Mac world can ever be harmed by outside influences?
You need to do a little research...