When checking Bitcoin prices, you need to keep in mind that there is no specific global Bitcoin price standard. Bitcoin is not tied to any currency, country or exchange. The question is the same as if you were asking: “Why is bread more expensive in this supermarket, or in this city/country compared to other countries?”. The short but precise answer is “because of supply and demand”. and maybe the transfer fee in South Korea is more expensive than other countries, I haven't tried it but this is my opinion.