And clearly, many african-americans and many women were not doing the steps needed to be talented enough to be able to make it big now. The most likely reason they did not do that, is probably because it just did not occur to them.
And in any case, there is this theory: if you pick any group of people at all, there are going to be a few people who are simply more able to do many things. Let's say these people are more talented and more intelligent. These people tend to work on what is currently 'intellectually trendy'. For example, a while back they would have been painters, another while back, they would have been writers, another while they would have been physicists, now they are technologists. These people search out a trendy intellectual effort and then spend their time developing their abilities there. This 'trend' is different for different groups, depending on the media that they are exposed to, and what the people around them are talking about.
Groups in America are pretty segregated, and there is a form of intellectual segregation betwen men and women. It leads to gender specific roles. It also leads to the effect observed above: Smart black guys did not start fiddling with computers 15 years ago, so they are not currently active in the tech industry.