I think this largely counts for a lot of things these days. People create their own echo chambers , even on here.
The western population are brainwashed, information is controlled, withheld, twisted to a narrative and people heavily using social media then trigger their algorithms to keep only seeing the same viewpoint.
Just look at the Israel conflict where even language is manipulated in reports. How many people genuinely thought trump would walk this election, because clearly in real life voters weren't voting Harris, all because they were so used to seeing their own opinions each day? Many other issues that are treated as right and wrong , even such as the trans debate. People see their own opinion, they just don't see the majority disagreeing with their viewpoint by design.
Everyone is brainwashed, what makes it so scary is that people will argue and defend the information fed to them without realising it was planted there for them to think. Anything they don't get from their information source must be lies/fake/propaganda. No wavering in their opinion, their opinion is right.