Why is the leaderboard important?
Does the leaderboard have benefits beyond human nature's desire to compete?
Read a book on gamification and it will all be clear. Quite an interesting field! If you need I can suggest some books :) Anyway 3 things "fire users' desire": Points, Badges, Leaderboards.
well you could also consider the mental encouragement boost to your self esteem? if you mean tangible benefits, sounds like your question is phrased identical to the answer, just move the first word to be the third word and append " not" to that word ;)