Bitcoin is a long way from becoming a currency you can live your life in. You also only have 7 transactions a second. But that doesn't mean Bitcoin isn't immensely valuable as a medium-term and long-term store of value
Honestly it is true that bitcoin cannot replace currency in the world because price is not stable just like the exchanges money to other country. I believe that eventhough bitcoin price is not stable it would not be a currency in the world.
It is actually getting its fare popularity among tech people in the world and the good thing with bitcoin is that everyone can pay for it outright without any government and bank regulations from the countries you make some commercial transactions with.