I don't get the question. You can only run macOS legally on a Mac, there's no other option. And any new-ish (ten years or so) Mac is able to download the latest supported macOS completely for free.
So the OS is basically included in the product (just like a washing machine or a car) and upgrades are free.
Legally, you can run macOS anywhere you want. Apple cannot and has not stopped anyone from doing that. There is no court of law anywhere which will prevent an end-user from doing what they want with macOS.
However, you most certainly are paying for the OS whenever you buy Apple's overpriced hardware. Perhaps the receipt does not state this fact, but we all know that the only way anyone will get macOS is if someone gives Apple money. So, the people giving Apple money are all paying for macOS... And if you're one of those people, you've paid for macOS.
Saying that you're not paying for the OS is like saying that you're not paying for solar panels when you sign a 15 year deal with some energy company middle-man. It's like saying that you're not paying the full price of a smartphone when you buy it subsidized from the phone carrier. You actually end up paying more for the solar panels and the smart phone in those cases. In this case, you're most likely paying more for the OS as well.
If you want to play games with semantics, anything you want can be true.
> Legally, you can run macOS anywhere you want. Apple cannot and has not stopped anyone from doing that. There is no court of law anywhere which will prevent an end-user from doing what they want with macOS.
I think you'll quickly find out that's not the case if you, for example, start a macOS VPS hosting company that doesn't use Macs or that lends them for shorter time periods than one day.
> Apple's overpriced hardware
This meme needs to die, now more than ever (because of Apple Silicon).
> ...for example, start a macOS VPS hosting company that doesn't use Macs or that lends them for shorter time periods than one day.
That's not an end-user doing whatever they want, that's a company providing macOS to end-users. End users can do whatever they want.
> Apple's overpriced hardware...This meme needs to die, now more than ever (because of Apple Silicon).
Apple Silicon has nothing to do with overpriced base systems, SSD/RAM upgrades and overpriced accessories. Everybody knows Apple hardware is overpriced.
The fact that you actually get less functionality out of Apple hardware adds to the cost. For instance, I have an old 2012 Mac Pro among many other machines in my home/office. The amount of time, money and effort I had to spend to keep this thing running was ridiculous. I had to buy an RX580 to be able to upgrade it to the latest OS and then I had to spend time researching how to fix their locked down piece of shit UEFI loader so I could boot into a better OS (that would be Manjaro). After that I had to spend hours working around all sorts of little Apple-specific oddities like accessing settings that would be in a BIOS on a better computer.
Apple Silicon adds to the cost too because it's incompatible with everything. Now you can do even less stuff with your Mac, but you can do it really fast!
Any other PC in the house would have just worked. This one looks cool though and it's built like a tank so I spent my time figuring it out.
So the OS is basically included in the product (just like a washing machine or a car) and upgrades are free.