Why are you still wearing a mask...wrong?

All the time I have people come in to work wearing a mask, which is fine normally, good for them, but they are wearing them on their chin, chin diaper style. Not covering up anything. Or at best just their mouth, sometimes. Nobody is making these people wear a mask anymore, so why are they doing it at all if they are just going to do it wrong? Is it an attempt at a political statement? A lack of education? I end up baffled for a while every time I see one of these people.