See! Even virus-writers don’t support Macs!
It’s not for lack of trying.
And the whole “there’s not enough Macs for them to go after” argument doesn’t work when people are writing viruses for cell phone operating systems with less than 200,000 possible victims. There are millions of Macs running OS X today.
As of yet, no successful OS X virus has ever been found in the wild. (Social engineering exploits do not count against ANY platform IMHO as the only OS that they need to succeed is the several million year old one between people’s ears.)