I just rediscovered this great quote:
A new scientific truth does not triumph by convincing its opponents and making them see the light, but rather because its opponents eventually die, and a new generation grows up that is familiar with it. - Max Planck
I believe this doesn't just relate to scientific truth, but truth in general. My Dad would say, "Experience is always in the first person," meaning that it's a good idea to learn from others, but most of the time we don't. There are great new truths to be had, but everyone is at a different point in the journey, with all the baggage that entails. Many of the most important and needful changes can't happen until there is a personal experience with the need for change. Mostly that happens one person at a time. There are those who think people would act differently if they only knew some bit of relevant knowledge, but more often than not, the reality is much more complicated than a simple lack of knowledge.
Change requires love, patience, help and encouragement, a willingness to learn from above, from below and from all those around you. It requires an absolute and deep conviction that you could really be wrong about something in a fundamental way. It requires a desire to improve and a motivation to exercise more effort than normal. It requires the courage to be wrong and fail again and again in the pursuit of new understanding. In the end, it often requires the willingness to forgo the due respect and esteem of others. Almost always it requires some kind of sacrifice. It is for all these reasons and many more, that change is hard. Thanks be to those who, despite all of this, do change. They make space for others to do the same.