> People are just deceiving themselves.

I agree and also find it unpleasant, but I wouldn't claim to be incredulous that someone would deliberately want to deceive themselves. We deceive ourselves all the time for all sorts of stupid and less stupid reasons. If you need money but hate your job, you have to convince yourself that somehow getting up every day grinding it out is worth it. If you don't need money but are addicted to it, or don't have any other hobbies, you deceive yourself into making your number higher.

If you're a bodybuilder you might have convinced yourself that a certain repulsive aesthetic is attractive, or if you have weight issues, you might intentionally deceive yourself into hating the consumption addictions that are your weakness.

Many people who are vegans do happen to convince themselves of remarkably implausible nonsense that I haven't really seen in others as much, but it's usually due to what I'd suspect are other underlying mental health issues—the two groups I've observed the most mistrust in medicine from are 30+ men and vegans.

The act of self-deception itself isn't rare though