Well, I know that thumbs up/down doesn't really determine if you're a good member of not.
You could be the best member and have more thumbs down than thumbs up because some people could be jealous/hate you for whatever reason.
I think that if staff sees a member helping out constantly, he or she would receive Ninja, Awesome, or Wizard badge. I really don't see a reason to have a new badge when there's already 3 that could suffice.
Says the ninja
But anyway, the 10,000 thumbs up would be way to difficult to keep track of.