You asked a good question for which I had no answer... until now: Success has been measured in both economic and societal benefits.
“By our most recent count, Thiel Fellows have generated more than $115 million in economic activity, including $64 million raised in venture funding; $28 million in product revenue; and nearly $24 million raised from company exits, grants, partnerships.. They have created more than 50 new companies and more than 220 jobs at those enterprises,” said Jim O’Neill, cofounder of the Thiel Fellowship and partner and chief operating officer at Mithril Capital Management. “The Thiel Fellowship has impacted the lives of many more people than just the fellows and their employees. They have also developed products that help other people get better jobs, that empower students and teachers, and that energize the world. Whether a fellow starts or joins a company, researches ideas, enables social change, or does something entirely new, the common thread among all of them is how they improve not just the world, but the lives of others.”
The 2015 application process is open, and incentivized for early submissions.