Adam Back, one of the most respected figures in cryptography and a key contributor to Bitcoin’s early development, has raised a surprising possibility: Satoshi Nakamoto, Bitcoin’s mysterious creator, may no longer control any of his legendary coins.

Speaking at Blockchain Paris Week, Back suggested that Satoshi’s massive fortune could have been lost—not intentionally, but due to a critical flaw in Bitcoin’s earliest infrastructure. In the beginning, users had to manually save a file called wallet.dat to back up their private keys. Every new transaction required a fresh backup. If that step was missed, the coins were permanently lost.

Back admitted frankly, “This could have happened. After all, he is human.”

The implications are enormous. In Bitcoin’s first year alone, roughly 2.5 million BTC were mined. Satoshi is widely believed to have mined between 500,000 and 1 million BTC — a fortune currently worth billions of dollars.

However, as Back pointed out, these figures are based entirely on mining pattern analysis and remain pure speculation. No one truly knows what happened to Satoshi’s coins.