As far as I know, bitcoin is created primarily to solve the problem of inflation. When the basic problem is the same amount of goods in the economy, people have the right to print money can print the amount of money arbitrarily. The result is severe inflation. So bitcoin is born to solve this problem. It is possible that even the creator of a bitcoin does not consider it a trading currency. Maybe he just thinks bitcoin is like a common currency value without inflation. Maybe that's why its transaction speed is limited later.