Satoshi Nakamoto mentioned issues such as Bitcoin’s energy consumption and legal scrutiny in his early emails

A batch of emails recently made public by Martii "Sirius" Malmi, an early collaborator on the Bitcoin code, shows that Satoshi Nakamoto warned in a May 2009 email that Bitcoin could become a significant consumer of energy. Satoshi wrote: "If it does grow to consume a lot of energy, I think it will still be less wasteful than the labor- and resource-intensive traditional banking activities it replaces. The cost will be more than paying for all the bricks-and-mortar buildings, skyscrapers, and junk mail Credit card offers cost billions in bank fees an order of magnitude lower. But it would be a travesty if we ultimately had to choose between economic freedom and protection.” Satoshi Nakamoto also foresaw non-financial uses for blockchain, saying: “Bitcoin is a distributed secure timestamp server for transactions. A few lines of code can create a transaction that contains anything that needs to be timestamped. Extra hash value." Satoshi was also concerned that labeling Bitcoin as an investment could attract legal scrutiny from authorities. He wrote: "I'm still reluctant to explicitly say 'consider it an investment', it's dangerous to say so and you should remove the bullet point. It's okay if they come to this conclusion on their own, but let's not do that describe".