Satan fell because He wanted to seize God’s throne. But the Father rewarded His Son Jesus with the throne of the earth, as a human, because He overcame.
Jesus overcame rejection, temptation, and pain. He was a faithful witness who learned obedience, even to death on the cross. And here Jesus offers to freely share with us this great reward of sharing His throne if we overcome as He overcame.
Jesus overcame by learning obedience. He overcame by His testimony, His witness. Even Jesus had to learn. That is why we are here on this earth. To learn to serve sacrificially, for that is who the Father desires to inherit the Kingdom, and reign over His new earth.
Many will not possess this inheritance. Like the children in the wilderness, the Father will still care for them as children. God will be their inheritance (for that is an irrevocable gift) and they will be His children. But ruling the land will only be for those with the courage to possess the land.
Further, this promise, that we can share the amazing, glorious reward of sharing His reign over all the earth, in harmony with Him and with other overcomers, is given to what seems to be the most self-centered and rebellious of all the churches. Even if we are rich, think we need nothing, we can receive this promise if we hear the voice of Jesus, repent, and follow Him.