I don't want to update something that works, updates may break
something. Look at our old computer that runs Windows 98, I've been
using it every day for everything for 15 years now and it works
without any problem, even though there's absolutely no antivirus or
Clearly it works for him. His argument is good.
If somebody is not going to dodgy websites, not installing software, let's say they just use Word, and Outlook Express and they don't open attachments.
I have seen middle aged non-computer users in the family that use a computer minimally, and some elderly in the family, just don't get malware on their computer. I suppose they could misspell a URL but they manage with the one or two URLs they visit, or the URLs come up in the address bar. Or they have a button on the bookmark bar that sends them to the URL.
If somebody can survive in this day and age with Windows 98 and not get anything in 15 years, they are doing better than others with lots of "protection".
I may be flamed or downvoted for saying this but i'm inclined to agree with him. Not that it works for anybody but that it works for him, with his style of computer use.
One way you could show a flaw in his argument, is by taking down his computer yourself, remotely, without installing any special software or malware on there (and without social engineering that abuses his trust in you), and it should be realistic i.e. something that really could happen that you see happening. Good luck trying to do that!
You should also educate him as to the risks of our times, like he may get email purporting to be from people he knows, telling him they've lost all their money. And he shouldn't fall for that.
I'm sure many people know some cautious computer users in their 60s and even those in their 80s/90s who do not "browse" the web, and are just not getting malware on their computer! Like somebody that only uses the television to watch the BBC News, somebody might only use their web browser to go to the BBC News website. There are people like that believe it or not, and it'd take a miracle for them to get malware on their computer!
David has mentioned there were days when IE and OE ran Active X without asking(though it could be configured to disable active X). And one could use Chrome and web mail. The former being a fast browser anyway, and the latter being very portable.