...according to Peter Thiel, founder and ex-CEO of Paypal and now president of his own venture capital firm.

But entrepreneurs need to remember that "most contrarian ideas are in fact bad. ... Give me an idea that's fundamentally true, but no one agrees with you," he told the 4,000 attendees of TieCon 2008. TIE is one of the Silicon Valley's largest mentoring organizations for entrepreneurs and startups.

Paypal was based on such a contrary idea. It succeeded in creating an Internet-based payment system because it learned from the mistakes of several predecessors who tried to implement flawed systems. After the failure of five or six predecessors, it became conventional wisdom that an effort to create an Internet payment system was doomed.

In 2004, Thiel invested $500,000 in a little known site called Facebook, an investment that has grown in value by 50 times on paper. A preceding venture "Friendster” had grown fast, then started to fade.

The consensus view at the time was, social networking has no real value," recalled Thiel.