Will the Alchemy Work?

Stir together a vast fortune, "big data" technology, the luxury of time, philanthropy, and intelligence higher than everyone else in the room, and one gets John and Laura Arnold [bold added]:

[John} Arnold, it turns out, had accumulated a fortune estimated at $4 billion in the past decade—only a handful of people on Wall Street made more during that time. Although he had not yet announced it, Arnold had decided to give almost all of it away. In October 2012, he closed his hedge fund, Centaurus Energy, and retired. In U.S. history, there may have never been a self-made individual with so much money who devoted himself to philanthropy at such a young age. [snip]

But at a time when charitable giving in the U.S. is still down from its peak in 2007, the Arnolds want to try something new and somewhat grander. John says the goal is to make "transformational" changes to society.[snip]

"We started with the broad mission of, 'How can we produce the most good?'" he says. His background as a trader, he says, is fundamental to the foundation's approach. He wants to spend a lot of time doing research and evaluating data, and then make a handful of big bets, even if they involve considerable risk.
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Is it possible to do good by defining the means (data analysis, money, long-range planning horizon) but leaving the ends somewhat vague? Given the Arnolds' track record, I wouldn't bet against them.