Ever meet the guy that is constantly shouting, how they don't care, and don't value what people have to say? It seems like for someone that "doesn't care", they spend a lot of time trying to convince others of that fact. It's almost like they care. Mostly because they do, and their insecurities are forcing them too.
You encounter this more with young people. Tend to be people that are adults, but only in a legal sense. They tend to come from bad situations, and their fake apathy is something they cling on to cope. With time they grow out it, or they end it all. Ending it all, is of course the ultimate expression of caring way too much.
You might ask why I am thinking about this. A fair question, I don't really know. It might be that I have not encountered one lately, almost like I am too old to have people young enough for this behavior around me. Feels good.