There is usually no specific age limit for the use of Bitcoin. However, countries may have legal age limits that apply to the use of Bitcoin. For example, in some countries, you may need to be over the age of 18 to buy and sell Bitcoin.

It is also recommended that people who want to invest or trade in Bitcoin should be financially literate. Therefore, it is important that young people do their research and understand the financial risks before deciding to use Bitcoin.

If it's just a matter of interest and not an investment, I would support a 10-year-old being interested in Bitcoin, but it's definitely too young for investment.