Twitter CEO Jack Dorsey's first tweet sold for $2.9 million on Sunday. The buyer said it's the Mona Lisa of tweets.

• An NFT version of Twitter CEO Jack Dorsey's first tweet sold at auction for $2.9 million.
• The tweet was as valuable as fine art, like the Mona Lisa, said the buyer.
• Observers said NFT buyers may be speculating, buying pieces they expect to resell in the future.

The buyer who paid $2.9 million for an NFT version of Twitter CEO Jack Dorsey's first tweet said he's valuing it like fine art - specifically the Mona Lisa.

On Sunday, Hakan Estavi, chief executive at at Bridge Oracle, had the highest bid in an online auction for the piece. Insider has reached out to Estavi for comment.

"This is not just a tweet!," Estavi said on Twitter. "I think years later people will realize the true value of this tweet, like the Mona Lisa painting."

Dorsey's message - "just setting up my twttr" - clocked in at 24 characters, including spaces, placing its value at more than $100,000 per character.

What made a tweet from 2006 so valuable? Even in the form of a non-fungible token, or NFT, with a digital signature from Dorsey, it was still just a few lines of code.

"An NFTs value is largely derived as a function of scarcity and speculation," said Tom C.W. Lin, a professor at Temple University's Beasley School of Law.

The value of high-priced NFTs - like, say, the $69 million NFT sold this month - comes from the combination of high demand and rarity, as with any piece of art. An NFT version of Dorsey's tweet is a digital object that can't be duplicated, making it scarce.

Lin added: "An NFT itself does not have much intrinsic value beyond those factors."

Demand for Dorsey's tweet started slowly. According to Valuables by Cent, where the auction was hosted, the chief executive created the auction for his own tweet.

The first offer was made on December 15, coming in at one dollar. Within a few weeks, the top offer was $3,500. But that offer was canceled by the bidder, sending the price back to zero.

After Dorsey tweeted a link to the auction in early March, bidders quickly entered nearly 30 offers, sending the price to $2.5 million. As of midday Sunday, that was still the highest bid.

Dorsey said he would convert the proceeds from Sunday's sale into bitcoin, then donate it to charity. He sent a tweet confirming his donation on Monday.

Skeptics and NFT novices may question whether a public tweet can truly qualify as scarce, commanding such a high price. After all, Dorsey's Twitter post had been live for all the world to see since March 2006. And it will continue to be live on Twitter even after Sunday's sale, so anyone can read it for free anytime they want.

It's right here:

So what exactly did the buyer get with an NFT version? That version would add a digital signature, making it a one-of-a-kind moment, akin to a work of signed art, according to the Valuables FAQ.

Dominik Schiener, cofounder and chairman of the IOTA Foundation, said anyone who buys an NFT version of a tweet is basically getting the "essence" of the tweet's value.

It's important that the buyer trusts both the auction website and the seller. Otherwise, they could just post a new NFT version someplace else, he said.

"In order for the tweet-NFT to be valuable, there has to be consensus that the platform and technology is a de-facto representation of scarcity," Schiener said via email. "If the world comes to an agreement that the NFT version of an asset on blockchain is 'real', then it means you are acquiring the 'essence' of that thing's value."

Dorsey's tweet might also be worth $2.9 million for collectors simply because they could resell in the future for an even higher price, said David McCarville, a director at Fennemore Craig.

He said the rise of the NFT market is being driven by early adopters who've made money from cryptocurrency. They may be seeing similar opportunities in the NFT market.

McCarville said: "These early adopters believe that they are in a position to be the first movers in a market that is still very new and therefore should enjoy significant appreciation in value."