For many people in the world, possibly the majority, whatever old hardware they happen to have, that is what they have, and there is no replacing it. There is

For many people in the world, possibly the majority, whatever old hardware they happen to have, that is what they have, and there is no replacing it. There is also something to be said for treating any functioning hardware as worth preserving, just because it already exists, just like a human's life is worth preserving, just because they're already alive. Also, for environmental reasons, because the environmental impact of manufacturing an entire new computer from scratch is much higher than the power saved by running a more efficient one. Finally, of course, there is simply personal preference, whether due to unique features (as mentioned in a sibling comment), lack of features you do not want, and sentimental value.