This article gives a decent summary - https://www.malwarebytes.com/mac-antivirus
And this one - https://www.macworld.com/article/672879/list-of-mac-viruses-malware-and-security-flaws.html
I’ve used Macs extensively since 1998 (running OS 8) so know my way about them reasonably well. I have used third party protections in the past but haven’t for a long time. I don’t think it is a bad idea though and I may again at some point in the future, but I currently judge my own risk to be small, and the impact of any infection small.
My Macs aren’t used for work and they both have independent and robust back up routines - hourly Time Machine iterative backups, online data back up and occasional disc imaging.
My bottom line is if you are a competent user and are not downloading software from questionable sources you will most likely be fine. But if you are averse to the small risk that does exist, or think that you may be duped into downloading tampered installers then buy the insurance that reputable AV and anti-malware provide.
I’ve not been affected and these days only download apps from trusted sources - that hasn’t always been the case though and I have helped others out who were less fortunate, or more accurately - they took ill informed risks by blindly downloading cracked applications from dodgy sources.
