Whenever bitcoin comes up in conversation, like many otherwise educated people, I say the same thing: “I doubt its viability as a currency, but the blockchain technology might be a game changer.”

I reckon this is the go-to line for everyone who wants to seem smart but doesn’t understand Bitcoin. Take, for example, JP Morgan CEO Jamie Dimon. Today (Jan. 9) he told Maria Bartiromo of Fox Business he took back his statement from September that bitcoin is a fraud that would end in tears.

“The bitcoin to me was always what the governments are gonna feel about bitcoin as it gets really big, and I just have a different opinion than other people,” he said. “I’m not interested that much in the subject at all.”

Perhaps he protests too much.

In April 2013, I went to a lecture called “Bitcoin: Currency, Commodity, or Con?” It was early days for bitcoin. I expected the room to be full of tech nerds, and people like me, who study the underground economy (and maybe a few criminals). I was wrong. The room was FULL of high-ranking financial executives. The sort of people who are too busy to go to lectures, it may have been one of the most high-powered gatherings I’ve ever been to. They were nervous.

Payments, the business of global wire transfers, credit-card processing etc., is big business for commercial banking. The blockchain technology could disrupt the industry. JP Morgan’s 2013 Annual report sounds terrified, expressing the hope that the bank’s sheer size will save it:

Payments. While this topic does keep us up at night due to the talent and innovation of the competition that would love to make us obsolete, we should point out that JPMorgan Chase is one of the biggest payment companies in the world (across credit cards, merchant payments, global wire transfers, etc.). We are even one of the biggest mobile payment companies. So in this space, there is both risk and opportunity. We have some good ideas and action plans so stay tuned!

It is hard to believe what kept JPMorgan up in 2013 Jamie Dimon does not think about at all now. The latest JP Morgan annual report does not mention blockchain or bitcoin. Perhaps the issue has been resolved. Or Dimon’s latest comments could be limited to speculating on bitcoin as an asset and he is still nervous about the blockchain technology behind bitcoin.

He did tell Bartiromo that “The blockchain is real.”