Human Capital

The (very) traditional capitalism was strongly relying on savings as a foundation for the investment capital. The investment capital in turn was essential to keep the economy wheels spinning, as most of the industries were capital-intensive. From mining to manufacturing to distribution. The reliance of savings also was justifying the large spread in wealth, as it was the savings of the wealthy providing the investment capital.

This model started breaking up roughly after the WWII and does not hold anymore. The majority of the capital needed today is the human capital. The fact there are many wealthy families in a country does not translate into the country's growth potential, if the middle class does not get broad access to proper education. And proper these days is not just high school. Honestly to be really prepared to contribute (and compete) a college or (better) a university is necessary. 

The problem with human capital (which the worlds' economies have become so dependent on) is it cannot be borrowed nor transferred at scale. And it takes way longer to accumulate. Also the time it takes to reap the returns on investments in an educational system are very long (relatively), making it less attractive for governments to spend money on, as the results will be well past their next election date.