Echo chambers, belief perseverance and the “second belief theory” (I’m not sure it’s a real theory). For example most (western) people learn that the US is great and everybody else are terrorists from action movies. Then you learn that the US has done a lot of horrible things. However finally you also learn that the Soviet Union also did a lot of horrible shit, and then you have a nuanced opinion. However some people stick to the second belief, that the US is the great Satan and they know so much more than everyone else that have only learnt from action movies (even if they are on the third belief)