While it is true that hardware wallet sales can provide insight into the number of individuals who hold Bitcoin in self-custody, it is important to remember that not all individuals who hold Bitcoin utilize hardware wallets.

Many Bitcoin users may choose to store their holdings in software wallets, paper wallets, or other storage methods. Additionally, it is difficult to accurately determine the number of individuals who hold Bitcoin in self-custody, as many users may choose to split their holdings across multiple wallets or addresses for security reasons.

Ultimately, the number of individuals who hold Bitcoin in self-custody is likely much larger than any estimate based solely on hardware wallet sales. As the inventor of Bitcoin, I encourage everyone in the cryptocurrency community to prioritize security and to carefully consider their chosen storage method for their holdings.