Satoshi mined the very first genesis block ever mined to generate the first bitcoins ever produced. The code is open source, meaning that anyone could take a look at how it works and validate that nothing fishy is going on under the hood. But even Satoshi had to run billions of computations and play the Proof of Work lottery in order to mine the first block. He couldn’t produce a forgery by faking the expenditure of the electricity required, even though he was the creator of the system.
