I doubt many MAJOR racists changed their minds at all.

For the sake of definition, I'm going to say a major racist is someone who actively hates a group and will go out of their way to watch them suffer. A minor racist could be a child of a major racist. They won't go out of their way to make them suffer, but they are suspicious of them and less likely to treat the group with equal respect. They don't have personal reasons for their hate, but they've been raised to accept the group as inferior.

Minor racists either lean into the racism, or they get out of that circle and expand their perspective.

Progress is generational. Our kids are generally more accepting than we are. Young adults today are more accepting of LGBT+ than my generation was, just like we were less racist than our parents or grandparents.

Major racists don't change their mind, they die off. We sadly won't see major change in our lifetime, but as long as we instill our good values to the next generation, and are willing to learn new ones from the younger generation, we'll get there.