Changing thoughts or ideas (being open-minded) for some people means changing their identity because these thoughts form their identity such as some religious people. For some, it means being vulnerable and "weak" because these thoughts form their knowledge base, like old naggy bosses. In general, changing thoughts is challenging because it lifts us from our comfort zone.
If we try to be more open-minded it will not only help us with racism or extremism. It goes beyond that, It will help us learn fast. Let me explain; The way our mind works is by forming patterns due to repetitions like memorizing a song or a language, these thinking patterns stick, and changing them becomes hard sometimes. Why children pick up faster then adults? they didn't develop these patterns yet so they are more open to new ideas.
Being open-minded is not hard, give any thought a chance, let it affects you, then decide if it for you or not.