Most of us have seen or heard of people *escaping* from cults. They are often shocked at how deeply they were indoctrinated and amazed at *reality*. We never doubt they know they were misled and brainwashed. We also know that those who *got out* have infrequently been able to convince others to leave.
While deeply entrenched in traditions or conformity people often lack the ability to analyze their behavior objectively. Especially when a large number of their peers exhibit the same groupthink model.
So, when a vegan (who was previously nonvegan for many years) says they feel like they *escaped* and they were *brainwashed* (and there are literally millions of vegans who use these words), who do you think is more aligned with reality? The one still supporting irrational blind-follower behaviors, or the one who *escaped* and can now see both sides clearly?
I was nonvegan for more than 30 years. I escaped the cult of carnism. I will ALWAYS live vegan, because I am no longer brainwashed.