Some British kid is left alive to learn witchcraft instead of being burned at the stake by his mortal parents. Also there's a bad guy who wants to take over the wizarding world because he was placed in the house that turns kids evil. Then there's the Dumbledoor guy who is supposed to be all powerful. But he mostly just sits back and watches children suffer so that they can learn something.
( This is my favorite quote from book 14)
Lucious: what are we going to do tonight Voldemort?
Voldemort: The same thing we do every night Lucious...TRY TO KILL HARRY POTTER!.....and maybe take over the world or something for a higher stakes plot than child murder.... I don't really have a justified reason, lets just do it!