Windows 7... pffft. Like I'd ever upgrade from MS-DOS based Windows 95...
Joking of course. In general, I found the offer by MS quite nice, to be able to upgrade (home edition) to Win10 for free. And I did that on a rig with DDR3, which is now some 10 years old, and Win10 worked fine on it as recently as 3 months ago (when I got me a new rig, and now with Win11), with the minimum requirements for Win10 quite similar to Win7 and 8.
So, unless someone is simply overwhelmed with the upgrade process, I don't really understand why one wouldn't want to upgrade at least to Win10.
Please tell me this isn't actually happening. I can't afford to upgrade my home computer to Windows 11 because of a trivial TPM requirement. Contrary to popular belief, I'm pretty sure TPMs do very little to actually increase system security. I really don't think secure boot is all of what it's hyped up to be and it's a major hassle to deal with.
TPM-modules exist, in some cases for less than $20. Whether the manufacturer of your MB offers a TPM-module for it, that is a question, which depends on what MB you actually have.
As for newer MBs and the minimum requirement for Win11, the cheapest combo with a CPU can be had for less than $100 (plus a bit for DDR4 RAM). That's still money of course, but just to be clear what the price tag is, in case there is a worry that it may take at least $500 worth of hardware just to be able to run Win11.
And as was mentioned, Win10 is an option as well.