I ask myself this question alot too. WTH is the point? if there are no skittles at the end of the rainbow then why shouldn't I be miserable and malcontent?
But there really is a point. It's better to have lived than to have never existed at all. That's really what it comes down to.
So many of my ancestors (and somewhere down the line you and I share the same ancestors) have struggled against all odds to survive and reproduce so that we could be here now. If, somewhere along the line one of them gave up and died before passing on their genes, I would have never seen the beautiful smile of my daughter, I would have never met the love of my life, never seen the beauty of this planet. Never experienced the awesomeness of alcoholic beverages etc.
Life is incredibly rare and precious. Live it up within your means while you can!