not everyone actually KNOWS what they're imbibing though. There are discrete pipelines of rhetoric that drip-feed poison that oftentimes isn't even noticeable until it's too late. Little baby-steps of escalation. Getting roofied is not full consent!

each human being comprises a wide foundation of autonomous sensory and telemetry systems feeding data up into a stack of reactive animal impulses of competing interests which present options to a capstone observer process that has executive influence in deciding which options to embrace and cultivate vs which ones to ignore and atrophy and that capstone, your actual SELF, is a much smaller piece of you than you think it is, and it CAN be overwhelmed by junk info flooding the lower sections.

People. Get. Brainwashed. People absolutely CAN and DO become prisoners within their own bodies as their willpower is overwhelmed and swallowed by propaganda and rhetoric, becoming possessed by an ideology that replaces them and transforms their body into a shambling zombie whose only goal is to SPREAD THE INFECTION. You can see it take hold whenever you're trying to tell someone something that opposes their worldview, watching their eyes glaze over mid-sentence before they are swept under the thrall of canned responses that they neither actually believe nor even fundamentally understand.

Mostly it happened to our parents and grandparents who drank the tea party's kool aid and then promptly got swept up into the MAGA cult, or worse, Q-Anon. There might be a shred of the person they used to be in there somewhere, but make no mistake, that person is not in control anymore. That person who loved you as family once has been replaced by a ghoul that will sacrifice you to the false god of its ideology now.

No matter how much high-minded philosophizing we pile on top of ourselves, deep down these bodies are still animals beholden to flawed instincts and senses that can be manipulated, misled by illusions, or even driven to outright hallucination.

TL;DR: YOU ARE NOT IMMUNE TO PROPAGANDA.

(but i've upvoted you because 'brainfucked' is DEFINITELY a valid alternative way to describe this shit XD)