The twin brothers dubbed the world's first "bitcoin billionaires" have predicted the controversial digital currency could increase in value by another 20 times from today's levels.
Speaking to Fox Business following the launch of the first bitcoin futures product on the Chicago Board Options Exchange (CBOE) on Sunday night, Cameron and Tyler Winklevoss challenged the naysayers to "put their money where their mouth is".
"We think bitcoin is gold 2.0," Cameron said. "It's a store of value, so today it's about a US$300 billion market cap, gold is at US$6 trillion, so we think it could very well go up another 20 times from today.
"We've been saying this since when bitcoin was a billion-dollar market cap. We've been in bitcoin about five years, it's grown about 300 times to this point, so we think it's definitely realistic that it could grow and disrupt gold and maybe even beyond that."
The Winklevoss twins are the founders of the Gemini Exchange — which the CBOE has partnered with for its futures product — and long-term bitcoin investors. In 2013, they bought US$11 million worth, accounting for around 1 per cent of total circulation at the time.
The pair first heard about bitcoin while on holidays.
"We were in Europe, we actually were on vacation, we had to get money to our accommodation, and it was so hard to get money from the US to Europe," Tyler said.
"The joke is if you want to get money from New York to London on a Friday night, go to JFK, jump on a plane with a bag of cash and you'll get there quicker than when you actually wire. This is the first money that's built for the internet."
They wouldn't comment on how much they still own, but said they had only ever sold or spent bitcoin twice in the past.
"I think Cameron bought some Legos, and we bought tickets to Virgin Galactic Space," Tyler said.
"Unfortunately we really overpaid, because bitcoin went up about 20 or 30 times. So we learned our lesson — we don't spend our bitcoin, we're long-term holders. We think it's a store of value much more than it is a currency."
You're on this mania curve. At some point in time there's got to be a levelling off
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Bitcoin has increased in value by more than 1500 per cent this year to reach a market capitalisation of more than US$280 billion, in what UBS describes as the "bubble to end all bubbles".
The launch of bitcoin futures, which allow investors to bet on the rise or fall of the currency, was widely seen as a success despite many major banks keeping their distance and the CBOE twice being forced to suspend trading due to major price swings.
"Whether it's a fraud, whether it's a bubble, whether it's legitimate, you will be able to express all of those thoughts in a transparent market place," CBOE chief executive Ed Tilly told Agence France-Presse.
After a wild weekend which saw massive sell-offs tank the price by more than 23 per cent, bitcoin rallied to a fresh record high of US$17,370 late on Monday, according to research site CoinDesk. Today it is trading for US$16,535.
Speaking on Fox Business, Tyler hit out at high-profile bitcoin detractors like JP Morgan boss Jamie Dimon, who has described it as a "fraud".
"This contract actually allows you to short bitcoin," he said.
"Talk is cheap. Now people can put their money with their mouth is, whether that's Jamie Dimon or someone else, they can be transparent about how much they're personally betting against bitcoin.
"This is the first bitcoin futures contract in the world, so we really have a truly two-sided market for the first time ever. It's going to increase liquidity, it's going to reduce volatility long-term and we think overall it's going to increase price discovery and transparency dramatically."
It came amid fresh warnings from regulators and experts about bitcoin "mania", with US securities regulator Joseph Borg telling CNBC on Monday some people were even borrowing money to invest in the cryptocurrency.
"We've seen mortgages being taken out to buy bitcoin," he said. "People do credit cards, equity lines. This is not something a guy who's making US$100,000 a year, who's got a mortgage and two kids in college ought to be invested in.
"You're on this mania curve. At some point in time there's got to be a levelling off. Cryptocurrency is here to stay. Blockchain is here to stay. Whether it is bitcoin or not, I don't know."
Shane Chanel, equities and derivatives adviser at ASR Wealth, said historically, when these sorts of things started to happen, it indicated a correction was near.
"A correction is inevitable like we saw during the 2000 tech bubble," he said in a note on Tuesday. "For example, we saw Amazon shares halve in value when the correction occurred. However, since then Amazon's shares are up over 7500 per cent."
Meanwhile, the US Securities and Exchange Commission has also warned investors against bitcoin and other cryptocurrencies, particularly those offered to investors under controversial initial coin offerings (ICOs).
ICOs are typically used by start-ups as a means of crowdfuding by offering newly issued cryptocurrency in exchange for cash or established currencies like bitcoin or ethereum.
"The world's social media platforms and financial markets are abuzz about cryptocurrencies and 'initial coin offerings'," SEC Chairman Jay Clayton said in a statement. "There are tales of fortunes made and dreamed to be made. We are hearing the familiar refrain, 'this time is different'."