We take part in these narratives and marches and isms because the whole acting out feels like a fulfillment of many of the deepest human desires: the desire to be a part of a larger tribe and to matter to the tribe, to make a difference for the benefit of mankind and the human world, to live a worthwhile life and push back the darkness, defeat the barbarian other, to correct the immoral and to have one's light take part in a brighter future.
What looks odd to me about these story-movements isn't so much that we act them out, we always have in one form or another, to form a world picture and try to try struggle to redeem the world through that picture is one of the centers of human life. What's odd is that over the last hundred years or so some groups have learned to weave these story-movements, to use mass media to cast the spell of a story-movement, for their own power and profit, and that it seems to work from time to time.
It frightens me to see so many so uncritically and unreflectively living out a story-movement. It must feel, when its presented through mass media and one's peers something like that's its being discovered or something, rather than force fed. It frightens me because I suspect on some level that my entire life is something like me acting out a conglomerate of these story-movements, that I am at least as much puppet and robot as I am free.
If you haven't got this one under your belt, it's worth it, peak Adam Curtis: