A culture, an organization, a country a city: large entities can take on a conglomerate personality. Sometimes this conglomerate personality is so strong that we relate to it in terms of the whole, forgetting that the entity is a big pile of people. Every entity, no matter how large is made up of individuals.
You will never be able to change a whole culture, country or city, but you can reach a person. And another person. And another person.
Related: Change The World.