They do the same as any other people! To communicate with people from all over the globe , to understand what's happening around , to maintain a strong economic links with the other countries ( knowing that South Korea is one of the strongest economies in the world ) and for hundreds of political reasons (what happened in 1953 still affect the area )…etc.

it's the language of the world

u make me laught at your naivety and this question ! English 's also the communication language in the world . It's very useful for u to make friend with everybody around the world . OK ?

You speak Arabic natively and have left this question in English. This explains it enough ;) Western and Eastern people look at the world in different ways and their way to look at the world is sometimes… pretty interesting. Therefore learning the language is the beginning to be able to know their thoughts, opinions, lifestyle and so on. It's like a window to show the country that you want to see.

sorry the same thing in korea