A number of people do not care enough for things getting better. The OS they are running is fine, it solves their problems and does not have gaping holes. But t

A number of people do not care enough for things getting better. The OS they are running is fine, it solves their problems and does not have gaping holes. But they do care a lot about things getting worse: something breaking during the upgrade, something degrading or becoming incompatible, and requiring more work just to get to the previous position. So an upgrade has basically no upside and a significant possible downside. I'd say that you either live in a rolling mode, when you spread small-scale fixing and adaptation efforts over a long time, or you stick to a particular release and only apply security updates, and never upgrade, but instead build your new iteration from scratch using new versions of everything.