I'm still on Windows 7 on a 2012 desktop. There's no reason for me to change. I've yet to run into any situation that has required me to upgrade. Since the world is generally web-first, the only thing that matters is Chrome and Firefox. Even running 4K video just required a codec upgrade as opposed to CPU upgrade. Yes there are security concerns but I'm pretty vigilant. I haven't run a virus scanner in 15 years, I'm…
To be blunt, this is a bad idea.
I'm sympathetic to the general motivation. I think the value and effectiveness of antivirus is generally overstated; it's often a replacement for vigilant browsing, and usually not an adequate replacement. If you keep to trusted sites, don't click email links, and don't ever unblock ads, you can do remarkably well for yourself. (Of course, if you've ever clicked some link and regretted it, it's time to start scanning or wiping.)
But you don't have to fall for spear-phishing or click shady ads to get into trouble. Since 2012, much less 2004, we've seen zero-days compromising servers and numerous other threats that could affect you indirectly. If your machine was Lenovo, it quite possibly came with malware. If you've used Sennheiser's setup app, your root certificate store may be poisoned. Further back, if you put Sony BMG music CDs into your machine, they may have given you a rootkit.
I don't worry about antivirus much for on-the-web protection; the threats most likely to reach me are the ones it doesn't protect against. But I think it's valuable to have something that keeps up with the history of other known screwups to help protect me against other, stranger threat vectors.