God is the ultimate power above everything. He has the final say.
He will place or allow whom he wishes to be a ruler/leader.
Didn’t he allow the Hebrews to be ruled by Nebuchadnezzar?
Your opinion of how rulers obtain or remain in power is stilted to the extreme, making God responsible for all of them in every case, taking His non-intervention to mean He is actively placing or approving every ruler over any people anywhere. Your perspective is juvenile, but understandable. What you need to grow in Grace and knoeledge to understand is that you will continue to be a sinner so long as you are alive. God does not approve of you continuing to be a sinner, as if He is responsible because He didn’t stop you from ever sinning again. The Catholic Church has a long and colorful History of discussion on permissive will which might help to inform you.