I have used Macs exclusively at home and at work since 2000 (my first computer was an Apple II, back in the day) and have never used any antiviral apps separate from what is already provided in macOS. At different times - generally in response to a well-publicized "threat" (which I suspect, more often than not, are antiviral app developers exaggerating in an attempt to create a market for themselves) - I tried a commercial antiviral/malware app, only to find that it slowed everything down. Worse, it continuously reported "suspicious activity," indicated by some loud noise & a large warning screen. This made me crazy in little more than hours, and I always removed the app (which, of course, is not a simple thing to do because it is pre-built to prevent "malware" from removing the protection, but could never seem to be able to distinguish me, as the admin user, from what it believed were attempts to corrupt the system).
Apple security is very thorough & frequently updated, to the point of literally being a nuisance. Without some command line hacks to disable features, macOS will not allow you to install anything it is not able to identify by a specific developer's "signature"; in fact, it will report that the app is damaged, and offer to move it to the trash bin if it cannot identify the developer (so imagine the panic users have when warez apps that have been hacked are reported as "damaged" and should be deleted...). Most importantly, macOS has "System Integrity Protection" at the root level, which Apple describes as, "[protecting] the entire system by preventing the execution of unauthorized code." SIP is the final line of defense between malicious hackers and the OS, but some hacked warez utilities now actually require the SIP be disabled in order to even run. That is a step too far for me, and I have abandoned apps that require disabling the SIP, leaving the OS completely unprotected. Can macOS be maliciously hacked by someone intent on doing harm? It is certainly possible, but very unlikely if only because the market share is small by comparison to MS Windows, and apparently more difficult and less lucrative an endeavor. Twenty-two years of using Macs and no viral infections perhaps is a false sense of security, which Mac user may live to regret, but so far, so good.