If btc is legally accepted in all countries then huge number of investors will increase. and the use of btc in various fields will increase.
what is your opinion about this?
It is highly imposible that all countries will adopt bitcoin as legal tender.
because every country already has a legal tender in the form of currency that is used as a means of payment.
If bitcoin is used as a legal tender, it can kill the country's local currency.
Yes, you are right, it is very unlikely that BTC will become a legal means of payment in all countries on this earth, including in my country, as mandated by the country's constitution that no other currency can be used as a medium of exchange other than the rupiah. Therefore, all types of currency other than rupiah are prohibited from being used, even if someone forces them to do so, they will be punished according to the regulations in my country.
but if it is intended for countries that do not have a strict constitutional message like in my country, it might happen, to be honest, this will be a big spike, but I really doubt that gas fees will be expensive and transaction congestion on the BTC network itself, so it won't would work effectively if only 50% of world transactions today used bitcoin.