Everything we say and do is, in principle, to help us survive, including interacting with others, due to the fact that we're social animals who need to feel a sense of belonging within their community (whatever that might be, since communities differ). So under that perspective, one could say that every single interaction is "fake" in the sense that our end goal is basically self-preservation, which could be considered selfish. But at the same time, that's just our nature to preserve ourselves, and we biologically can't help that fact. So even though that’s technically the case, I would still say that people do genuinely care about other people...at times. Other times, however, it really is completely and utterly fake.