"We need to create products that have better hit rates than that," he said.
Bitcoin also needs to become easier to use. It's simpler to explain the value proposition of Bitcoin than it is to show someone how to actually use it, Cameron Winklevoss said. "That should be the other way around."
But the brothers are clearly believers in the virtual currency. They started their talk loftily, with a quote from Mahatma Gandhi: "First they ignore you, then they laugh at you, then they fight you, then you win." They believe that will be the trajectory for Bitcoin, too.
The surge in Bitcoin's value in March and April wasn't a bubble or a sign of mania, they said, it was just "rapid adoption". And while the price of Bitcoins can fluctuate sharply -- something skeptics point to as a big drawback -- "the trend is upwards," Cameron Winklevoss said.
"We've bet on the horse and not the donkey here," he said.
There's a proud geek culture at the event, and Friday's activities wrapped up with a group outing to the theater across the street, to watch "Star Trek Into Darkness."
Bitcoin 2013 continues Saturday and Sunday with talks about the evolution of the technology platform, regulations, security and other topics.
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