It's a common theme in history, someone, usually smart powerful brutal etc manages to make himself the man god/ruler somewhere. When he dies, his son that he has raised carries the whole thing on, but when he dies, the third is often an idiot, believing, because this is how it has always been, that he's like the son of god for real and is just a nasty spoiled brat and so the decline starts...

Or, it's hard to carry a dynasty over more than 3 generations.