If there’s one kind of user you can’t encourage to upgrade to Windows 10 for whatever reason, it’s the privacy advocate that has the fear of security compromises. Of course there may be childish trolls trying to think and talk in a negative way about privacy advocates over Windows 10 stuff and especially that they think that Windows 7 and 8.1 users are not caring for the new technology on the outside or something. There have been tools that allow you to remove the Windows 10 installation files stored on the Windows 7 or 8.1 partition as well as to block upgrades to Windows 10. Maybe some hardware incompatibility, performance drop or other issues were the reasons against the upgrades to Windows 10 but I think that privacy is like the number one issue for me unless the edition of Windows 10 is Enterprise. Other reasons may regard things like some updates may break the OS or something like your computer is not able to boot up or some sort because of that or maybe new things are not performing well or anything like that.
The challenge between users and Microsoft continues with various workarounds that disable the updates along with newer updates that download the same Windows 10 installation files by undoing those workarounds and restoring certain stuffs done by those workarounds.