He wouldn't really have a pool of over 20 million machines. First they'd all have to be online and exposed to the Internet. You'd have to scan millions of boxes to find one susceptiple Mac box. So if I wrote an exploit against an unpatched OS X box, what are the odds I'd find 20 million available to attack? And like I said, no one would really sing his praises because the damage would be very limited and the fame gained wouldn't be worth the risk and time committed to writing the virus.
The same reason why my OS I wrote in 2001 hasn't been attacked to date. Other than a few M$ lovers saying see it was hacked, no one else would care.
Well, all I know is that I'm loving this PowerPC G3 with 384 MB of memory running OS X more and more each day. (lets see a PC with equivalent processing power run XP!)
Macintosh does drive me nuts though with their stupid incompatibility issues (some programs just aren't written for them), and those that are, sometimes (apparently) can't be updated, like my Adobe Reader. I have version 5.2 and it's always telling me "There's an updated version of Adobe online" but when I go to the website, the only one available for my OS (10.1.5) is the same version I already have! I think Adobe is on version 7 by now, and I'm stuck back in version 5, simply because I don't have the latest OS.
When Apple fixes it so that you don't have to have the absolute LATEST OS to run the latest applications, then that's really going to be the selling point for me. That, and the incompatibility issue.
As far as security goes, I haven't had to install virus protection, firewall, or spyware program one on this machine and it's still running like a charm. Anyone who says Windows and Macs are the same, security wise, is absolutely wrong, and this comes from a computer dummy like me. Even I can see that Windows is as leaky as a sieve.
It's not the number of infections, it's the fame of being the first, the l33t who was the one who took down OS X. In any case, numbers don't matter. Mac OS prior to OS X has lots of viruses even with the tiny marketshare, and there are probably at least as many copies of OS X running as the older OSs. The writers obviously thought pre OS X was worth their time. Why not now, when Mac is more popular than ever?