Though the mega-rich may be spending more on education, access to quality education has never been cheaper or as easily available (I just took a University Machine Learning Course on Coursera and didn't pay a thing).
David Karp was likely on his way to being an upper-middle-class web developer, who then created Tumblr and joined the mega-rich. It wasn't a 0-sum game. Nobody had to loose for Karp to win.
Lastly, her concerns for what the current or future environment holds for the working class, the market decides the rates of pay, and it is due to the market that incomes have somewhat stagnated (if they truly have). The mega-rich may be getting richer on the backs of those workers, but they are also loosing billions in the same environment. Their is a constant transfer of wealth, and as long as their is somebody else willing and capable of doing your job for less, corporate fiscal responsibility for the most part requires that the lower cost employee get the job.
We seem to not complain when prices for goods decline over time, but don't recognize that those declines are matched by a decline in purchasing power. It isn't the responsibility of business to ensure that we are constantly making more and more money, it is their responsibility to ensure that we are able to live a comfortable and happy life so that we can come back to work for them day after day.