I downvoted this answer : Can we find the perimeter of a triangle given only its base and height? , because the answer was really bad. But to my surprise, 1 point was deducted from my reputation (https://math.stackexchange.com/users/93616/sawarnik?tab=reputation). I don't mind that much, but what, why .. this has happened?
This is completely by design. See the privilege page:
What happens when I vote down?
When you vote down, you are nudging that content "down" the page, so it will be seen by fewer people. Voting down answers is not something we want you to take lightly, so it is not free.
- Downvotes remove 2 reputation from the post owner.
- Downvotes on answers remove 1 reputation from you, the voter.
- Downvotes on questions are free. (Why?)