You clearly haven't met a lot of your average PC or phone user then. Most people don't care about getting the newest and best thing. If a thing still works, they'll use it until it doesn't anymore, however long that is. You have no idea the kinds of PCs I saw people using when I worked as a technician. People just don't have an interest in getting new tech unless they're forced to, because they largely aren't interested in tech. They're interested in document processing, watching videos, listening to music and dealing with their pictures. And they don't care how old the device is they're doing it on.
In addition, they don't want to spend money on it. They'd rather spend money on things they actually care about. Festivals, clubs, vacations, a new TV, a car, restaurants, whatever. Your average non-tech person is happy if they don't have to spend anything on gadgets for 10 years.
My mum was still happily on some 8 year old iphone, I'm not even sure which one that was, and then got really annoyed that she had to upgrade just because her banking apps stopped updating and wouldn't log in anymore. It's just pure and complete e-waste.