Book: The Deathly Hallows This interaction signalled the start of the war and the wizarding world was approaching the muggle world to inform them to prepare themselves. If Voldemort defeated everyone who stood against him in the wizarding world, there wouldn't be anyone to stop him from mass genocide and wiping out the entire human existence to promote a pure-blood bloodline. As easy as some people think that it would be to run a country, imagine having to prepare the people of your nation for a war that they cannot win, against magical beings that should not exist.
