Every business that has connected devices should be running an AV solution, at least for Windows, which is the vast majority of users. In many sectors, it is a requirement to do business. I've never worked in a Linux based business environment, so I'm not sure what the AV solutions are. Many reputable businesses will have network wide monitoring via SIEM tools and other agents.

AV does exist for the end user's security, generally even the likes of Kaspersky. The inherent nature of running at the kernel level means that if something malfunctions, malicious or not, the effects can be significant. Generally speaking, these products aren't malicious because that's bad for business. The problem with companies like Kaspersky is that they have to comply with government requests which could mean access to private information.

The most important part of IT security is the human element. Don't click bad links, don't give out secret information, etc. AV products help when people mess up but also help protect against drive-by threats that don't require human interaction.

I don't run anything in my person Linux machines and used free Windows Defender on Windows for years. For anything not needing corporate level security, the free Defender is going to be more than enough and in most cases the best option for performance, not just cost.