MS forced the Win 8.1 update on users. Opting out required manual modification of the registry to turn off the update notice. Many users had problems after being forced to accept the update to 8.1. This is all documented at MS community forums and elsewhere.
It’s also documented that there was a serious flaw in the 8.0 kernel that forced everyone to update to 8.1. If you didn’t upgrade to 8.1, literally every security and kernel-level update would not work. Microsoft did a good thing with 8.1, because there were security vulnerabilities that would’ve been catastrophic to them had they not.