The 20th century was created by idealism. Communism and fascism and Nazism are all based on idealized systems, what the world should be ideally, and how it isn’t what it should be, and therefore we’re entitled to change it radically and take control of it in order to do so.
For most people on an individual level most the time, their future still feels very different from that of other people. We live in a world, for example, of enormous income inequality, right. So even though there is a global economy, it certainly doesn’t feel like one’s sort of day-to-day fate or destiny is linked to those of people around the world, even if it is in very invisible kinds of ways.