A lot of Windows 10 adoptions were due to free upgrades that worked with the hardware people were using at the time, while supporting newly released hardware.
I'm not sure what an "upgrade" to Windows is supposed to do. Like the programs which were written to work with the older versions of Windows, it (and they) has (have) matured to the point that the only way to sell is to offer subscriptions and the upgrades offer little benefit to the users.
