일본어 왜 공부하고 싶습니까? 일본어가 상관없을 것 같습니다.

Don't waste your time (and money) in learning Japanese (일본어).  Japan is in PERMANENT decline.

Japanese is easy for native Koreans to learn.  You have heard from your friends, or you know it for yourself, that native Koreans can learn competent Japanese within one year.  That is not a good reason to learn Japanese.   Japan is in PERMANENT decline.  Its influence in the world has peaked long ago.  Here is why.

1.  Japan's population is old.  It is a well-known fact that the Japanese live longer than the global average.  Some say it is due to the large amount of seafood consumed there.  It doesn't really matter why.  The point is that the average age of the Japanese population is far greater than other countries in the Asia, and the world.  Why does this matter?  Young people drive innovation, old people do not.  Companies target younger buyers for a reason:  they spend more money than older people.  One very good reason that Korea has caught up to, and in many cases, surpassed Japanese consumer electronic companies?  The younger, more demanding population of Korea has made LG, Samsung, and others to continue to make changes to consumer products continuously.  Think about Korea for a moment.  When there is a new product that falls behind, does it ever catch up?  Look at LG Electronics now in 휴대폰.  Remember the Chocolate?  It is now long forgotten due to the iPhone and Samsung android smartphones.  10 years ago, Panasonic, Toshiba, and Hitachi were signifcant consumer electronics brands in the U.S.  Now?  All but gone, and surpassed by LG and Samsung TVs.

2.  Japan is debt-ridden.  The size of the governmental debt is enormous.  One reason for the economic decline of Japan, and the failure of the Japanese government to stimulate the economy is because it cannot afford it.  Coupled with a declining population, who will be able to repay this debt?  There are fewer taxpayers to pay, and less profitable Japanese companies to pay corporate taxes as well.

3.  China, China, China.  Koreans are aware that China and Japan have a long history of animosity.  More than that, China's enormous population and natural resource needs will dominate the attention of people and companies on a global basis.  In the U.S., there is almost no mention of Japan as a target market.  China, and to a lesser extent, India are far more important to the future of corporations.

This is only a partial list.  Japanese is, no doubt, easier for native Koreans to learn.  Nevertheless, English is, and will continue to be, the universally accept language of business.  Since Korea must focus on business on a global basis, English is far more important.  Chinese is of course important due to the fact that it is close to Korea, and the world's most populous nation.    Japan, and Japanese, are in decline, and will continue to be for the forseeable future.  So, unless you are working at a job that is focused on Japanese tourists or tourism to Japan, studying Japanese will continue to be less important to Koreans.