I guess it's a good question how do you know if you don't have a virus scanner. I have 2 music PC's and 2 laptops, everything is connected to the net, although the 2 PC's don't surf or have email etc, the only thing they do is things similar to Cakes CC, you know, stuff that I trust that connects and updates at my say so, never automatically, unless there is no choice, but I don't think I have anything like that. The 2 laptops that do do all the net work both run avast and that's it, nothing else. Anything that I download that isn't done from within any app/plugin, whatever on the music PC's gets scanned on the Laptops, then I pass them on to the PC's.
Now I don't know much about this, but As far as I know, no outside connection can be made to anything on my side of the router, without me initiating contact first, you can check whether your computer is visible on the net through sites such as Shields Up etc, and it tells me that nothing on my end responds to any of it's probes from the outside, so to anything looking to get in somewhere it appears there is nothing to get into because it gets no response. That is my simple understanding, and again I don't know much about it, don't really want to know, I am happy with that.
How do I know the PC's don't have a Virus ? I guess I don't because they don't have any Antivirus stuff on them, and any Windows stuff is deactivated. But I can if I choose scan them from one of the laptops, either all files or individual files, but I don't bother. I guess everything runs like clockwork, money isn't disappearing out of my bank accounts, well not unknowingly anyway ? nothing is stealing the serials and install codes for all my software (it's all encrypted anyway) if there is any virus, it's certainly not making itself known, nor is it causing me any problems that I am aware of, and that has been the case for nearly 20 years, apart from the once back in '98, which was caused by transferring an infected file of a friends zip drive, I did learn from that.
So, like I said, don't know much about it, know what I need to know, don't really care to know anymore until I need to, but I do know that I feel safe and comfortable running the way I am, I feel confident I don't have any nasties, and if I do they aren't causing me any problems, and haven't been for 20 years.
If you feel comfortable having antivirus, malware stuff, firewalls whatever, that's great, go for your life, If you feel comfortable with just an antivirus prog, that's great, go for it, and if you feel comfortable with nothing, more power to you.
Everyone's situation is different, each person should know there own situation and what they need, it's up to the individual to do what they see fit. We are all responsible for our own protection on the net, so it's no good blaming Joe Blow because he doesn't have an antivirus, you are responsible for yourself, besides, NO product picks up everything, not even close.