You need a certain amount of karma to downvote. I think it's 500, but I'm not sure because I don't have that much yet. :)
Edit: it's confirmed at 501: https://news.ycombinator.com/item?id=12074198
Edit: it's confirmed at 501: https://news.ycombinator.com/item?id=12074198
Edited to add: PSYCH!! Now it's going to take 4 upvotes to get super powers. BWAHAHAHA!!
Edited to add #2: Just kidding! You're 2 upvotes away again!
P.S. Dear friends, I'm sorry. I won't abuse my vast and terrible ability to grant or deny imaginary Internet points ever again. -xf