It's interesting to note AV usage through the scale of increasing computer savviness.

Clueless - Runs whatever their PC came with, if anything.
Normal - Installs an alternate browser and some crappy AV solution.
Clever - Installs an alternate browser and claims AV isn't necessary because they're clever.
Informed - Installs an alternate browser, exercises good caution to avoid malware when possible, but still runs a good AV package to protect against that which can't be avoided simply by being a clever user.

Only those ignorant of security and malware in this modern age assume that they can be safe because they know to hover over links to see where they're going, refuse to open attachments from those they don't know, and other such basic things. If your computer is connected to the Internet, you're vulnerable no matter who is sitting at the keyboard. If your computer is a PC you bought in 1992 that never has anything new installed on it and doesn't have a NIC, congratulations, that boring system is safe.