I have never had one

Just one question. How would you know if you didn't have a anti-virus? :)

The answer; you wouldn't.

The idea that "Linux doesn't have viruses" is a great way to foster a bunch of people into NOT using an anti-virus under false pretence, so that when one ultimately comes to light, you have no protection.

If the last few years has shown us anything, it's that we really don't know anything about our operating systems. The amount of bad code that's been found to be dangerous or just generally exploitable is just amazing. Some if not most of it being 10+ years old code that was never reviewed. This is again where a false pretence of "it's open source, so that means more eyes on it" sets people up into believing they're safe just because it's open source.

I'd say it's better to be safe than sorry. It's the main reason I run Fedora any more. SELinux has been shown and proven to mitigate many or all of the recent exploits ( at least, the ones with fancy names beyond their CVE number ). Though not exclusive to Fedora, it is pretty handy to have it up and running perfectly.

Same for having a firewall up to block not just known bad incoming, but to also block any unwanted outgoing connections.

Never rely on security through obscurity alone.