Is bitcoin unsuitable as a national currency?

Could you elaborate on why some believe Bitcoin may not be suitable as a national currency? Are there concerns over its volatility, scalability, or lack of regulation? How might these factors impact its ability to function as a stable and reliable means of exchange and store of value on a national level? Additionally, what alternative cryptocurrencies or traditional forms of money might be seen as more suitable options for fulfilling the roles and responsibilities of a national currency?