I can’t remember where I heard it now, I think maybe on a course, but [citation needed] people only change their values by living them.

For example, you may think people with a different coloured skin are bad people. You may have been raised to think this, and it’s one of your core beliefs. No amount of data or arguing can change that view if it’s a core belief. The only way to change it is by living the value and finding out that your values are conflicting with your own experience. With the above example, this may mean becoming friends with someone of a different skin colour. Your core belief is that people with that skin colour are bad people, but your friend is not a bad person, so you have a conflict that may change your value. Seeing someone do something good on TV is not going to change your value, because you can just assume they are doing it with self-serving motivations.

Another example is that you may strongly believe that guns should not be restricted, until your toddler shoots themself and then suddenly your core value has been challenged.

The media is full of stories of people who believed one thing and then life proved them wrong (was there a subreddit about leopards eating faces or something?)