I'm also not using one, but each of our usage patterns differ so what might work for one of us, certainly doesn't apply to each and every one of us as well.
For example, for a lot of business stuff, I'm mostly using cloud (G Suite), have no offline email clients and I'm pretty much wary of what I allow in my browser (Firefox), thus I'm always using some sort of stuff blocking certain scripts etc. (used to be NoScript, now it's uBlock and while back when Flash was rampant, my very first addon to always install was Flashblock).
Thought I still have installed clamav, and while it's not running in the background and scanning things, the freshclam (regularly updating virus definitions) module is. Even though I know clamav isn't perfect (but then which AV solution is?), it's nice to know I can quickly scan something if I ever wanted to. Can't seem to remember I ever did.
On Win clients in the office, we use Bitdefender (Endpoint Security) and while they have something for Linux (
https://www.bitdefender.com/business/antivirus-for-unices.html), I'm not comfortable installing something like that. It's neither in the repository nor open-source. I feel like just installing that would pose a bigger compromise of integrity of my system than not having any AV solution.