There are ghosts and there are ghosts. Some are ghosts due to the agency of death and others courtesy the living.
Humans are perhaps the only creatures who have mastered the art of creating ghosts. We can ignore what and whom we don’t wish to see, we can walk through people, ignore them and treat them in many ways as if they don’t exist, at times with them standing right next to you. We can make people feel like they don’t exist and don’t deserve to. It’s the art of making people feel alone in a crowd, an alien among like minded people. And this is what we achieve with our ‘superior’ intelligence and high emotional quotient.