Antivirus software is fundamentally reactive in nature, not proactive, and I don't run antivirus software to catch novel malware. That's mitigated in other way

Antivirus software is fundamentally reactive in nature, not proactive, and I don't run antivirus software to catch novel malware. That's mitigated in other ways (which largely amount to good hygiene and disaster recovery planning). Rather, I run antivirus software to prevent vulnerabilities due to human error and known threats, and in this regard it functions admirably. Think of it as one of the latter lines of defense in a multi-layer strategy. We are human; we trust our family, friends, and colleagues innately; and even the best of us makes mistakes. One tiny mistake, one shortcut---maybe not even by ourselves but by someone inside our circle of trust---and even security experts can end up running malware. Antivirus acts as a backstop, a last ditch defense predicated on the likelihood that the malicious code in question is well known. I don't know where you got your numbers from, but I've run enterprise antivirus for about 15 years now. I haven't seen anything target the scan engine. I have hundreds of thousands of instances where someone ran malware and the scan engine caught it, sometimes even just using heuristic signatures. So you do you. I'm going to continue running it even though I know it's reactive.