That's a neat idea. Except that this would not be a manually awardable badge but based on a rule (10,000+ reputation). The other problem is that right now the highest reputation held by anybody on the forum is @Henry Ng Tsz Kiu's at ~2,000. 10,000+ reputation seems like quite a lofty goal if nobody in the whole history of the website since the early 2000's has ever achieved it!