Some people will have ideas they're stuck to, and will stay stuck to, no matter what they see, hear or experience.
Even if you have convincing evidence. Even ifyou've  used their own words against them. Even if they have physically experienced the truth, they will stick to their (factually incorrect) beliefs.
Not because they want to be difficult. We get beliefs hard wired into us as youth that are nearly impossible to unlearn, short of a conscious choice to reject them or a crisis situation (a near death experience, for example) that causes us to question everything. These two things rarely happen to most people.
Don't try to beat facts into the head of idiots. In their eyes, you're the idiot who doesn't understand that you can't change their mind.