So I think God wanted satan to have his kingdom on earth, to make it evident what that would lead to, and also to show satan and everyone that even a sinful person can "hate" his sinfulness and wish to get rid of it and to completely conform to God's will.
Please think for a moment, darlin. Just think without any interference from a book, your upbringing, or anything you've come to rely on more than your own sense of logic.