If the Lord God Almighty offered you the choice of either remaining in the earth or of returning to your place in hell, what would you do? That is the choice he has offered to the demons from hell, and knowing what they now know, they all have chosen to return to their place in hell. What they wanted was real life, not a life lived in a body that was stolen from an unsuspecting victim of subterfuge.
Perhaps at the end of this millennium, God will find a way to separate one demon from another, and determine who can be given eternal life, who has repented of their rebellion, and who is now willing to do things God's way. Perhaps there really is a way from hell back into Eden.