And they said bitcoin would never work as a currency.

While that might be true for small transactions - for now - real-estate markets across the US are increasingly demonstrating that bitcoin is a viable medium of exchange. Case in point: the seller of a luxury Miami condo will only accept payment in bitcoin. The asking price - according to real-estate listings site Redfin - 33 bitcoins, or about $550,000 at bitcoin’s present valuation.

According to Redfin, this is the first time a seller is exclusively accepting payment in bitcoin. The seller’s identity wasn’t immediately clear.

It begins: Miami condo on sale for 33 bitcoins - seller won't accept any other currency. First time that's happened in U.S., per Redfin https://t.co/hAvnpcL5zX — Mike Rosenberg (@ByRosenberg) December 13, 2017

But while this might be the first time that Redfin has noticed the phenomenon, homesellers have been asking to be paid in bitcoin since at least 2013, when an anonymous seller of a luxury condo in the Trump Soho of all places listed the price as 24,700 bitcoin, according to the Daily News. While this sale was t\he first that was documented in the media, it’s also notable that it occurred before the first bitcoin bubble burst.

Also over the summer, a realtor in Texas revealed that one of her clients had accepted payment for their home in bitcoin. The number of coins – and the identity of the seller and buyer – weren’t disclosed.

And as we recently reported, more realtors in hot markets like New York City and Miami are demanding to be paid in cryptocurrency, sometimes exclusively.

This trend in broader crypto acceptance - contrary to mainstream media reports - is undoubtedly a factor behind the unprecedented price appreciation whch has seen bitcoin soar from $1,000 to $19,000 in 2017.

Meanwhile, any buyer who has accepted bitcoin as payment and kept it, has so far managed to generate a staggering profit, given the digital currency’s aggressive appreciation. The real test will come after the digital currency inevitably tanks again.