Internalized logical fallacies combined with perceived (or real) trauma along with a lack of critical thinking skills or self awareness required to understand that their thinking is illogical.

The brain is a dumb piece of meat that was shocking into awakening and it is scrambling to make sense of the world and its experiences. It doesn’t do a good job if left to its own devices and very often makes mistakes that if not rectified early on can become near impossible to unlearn due to cognitive dissonance.