People murder their children every 5 days in America. That means that 265 people have wiped out their families since Casey killed her kids. In almost all cases, the father is the perpetrator. Do you know the names, or faces of any of those hundreds of men?
Casey killed her kids because she was nuts. Not even the prosecution disputes this.
People hate her because misogyny and ableism. If she was a man and did it for insurance money, this would barely make the local news.