why should we eat if we are going to be hungry again? why should we bath if we are going to be dirty again? Did you say "to fulfill our needs?"

The answer is simple my dear friend, It is to gain experience, No not physically but mentally more specifically spiritually, yes to gain all kind of experience, all kind of knowledge (to which meditaters called infinite knowledge) we are living here, because it was the desire of our soul to gain such experience that's why we took birth in this particular body.The Goal is to get the eternity that will come when we have no desire left.

Read "Jiddu Krishnamuthy" you will get your answer in detail.

P.S. i tried to summarize the answer otherwise it is really a waste aspect to explore.

P.P.S. this question was taged in "Big Philosophical Question" so i answered in philosophical aspect only otherwise you may also get the answer "to make the world a better place" or "to spread happiness".