Well, hang on here. I've run some flavor of Mac OS since 1979 (truth be told a bit off and on, but lots more on than off) and I have never suffered a virus either. I'm not caviler about it though...I run Little Snitch, an AV, have inbound firewalls rules set, keep up on my patches and get my pR0n through a sandbox VM. I see no need to tempt fate.
I also do the same on my Nix and Win boxes as well, with the same results (I did get a virus back in 1995 on a Windows box, which is when I started to tighten up the defenses a bit.)