I would say that this statement is not entirely accurate and is quite critical and doubtful. While it is true that in many countries, bitcoin is not yet widely accepted as a legal means of transaction, this does not mean that it cannot be used as a currency. Can you please provide the source of your information stating that Bitcoin is not yet legal as a means of transaction in most countries?
What I mean is that bitcoin is not yet legal as a legal means of payment in some countries and there are still many product/service sellers who do not accept bitcoin as a means of payment.
In general, bitcoin can be used as a legal means of payment, but government regulations cannot be ignored because there will be sanctions for those who violate them. Therefore not all countries and people use bitcoins as a means of payment, both direct sales and online and you have explained below?
"Bitcoin is not legal tender in most countries, meaning that merchants and individuals are not required to accept it as payment for goods and services. However, it can still be used as tender in many cases, especially in online transactions."