Because it's against the law, because there are other drivers on the road who might be endangered, because in some areas you could end up smashing into something like a moose (which can kill you even at much lower speeds), in the winter, road conditions aren't optimal, etc.
I can see how the "points" part of the original title could be turned into a full stop, but how the "speeding" part ended up in a Sanatorium sentence, I don't know.
