Of course there is always untapped potential, for the time being. That is why there are still startups and entrepreneurs, who try to release that potential. But it is not as simple as hiring diverse genders and races.
It is simply a hard problem to enable people to make the most out of their talents and potentials.
The Tom Mueller case seems to illustrate that well. What if there had been no SpaceX during his lifetime. Who would have been to blame? What would there have to be done? Perhaps Tom Mueller would have started his own Space company? Or maybe not. But whose duty would it supposedly be to provide a space company for people like him to work at?
Most people are not even sure how to enable their own children to make the most of their talents (or to develop some talents to begin with) - let alone some strangers. I think that also shows that it is not primarily an issue of diversity. We simply don't know enough about developing talents and making the most out of life yet. So we experiment - sometimes it works out, and sometimes it doesn't.
What exactly made Tom Mueller obsessed with rockets? If I want my kids to become rocket scientists, should I send them to lumber jack camps in the summer?