Robbery is a technical skill, especially when you want to rob an entire dynasty, and that dynasty is ruled by cultivators. It gets even harder.
But as the saying goes, it's easier to fight your way into the capital than to pass the examinations and enter it. Li Qishuo, who transmigrates into the body of the Third Prince of Great Yan, thinks that retaking the realm will make his seat on the throne more secure.
Factional strife? Great, keep fighting. How am I supposed to develop the country if you don't squabble?
Aristocratic clans monopolize the court? Even better. Where else would I find talented people to serve me?
The eunuch faction meddles in government? Well, you have to admit, people really do get things done when you pay them.
Warlords carving up the realm? Hard to say, since Li Qishuo himself is the biggest warlord in Great Yan.
Anyway, Great Yan looks doomed at first glance. Since it's going to fall apart anyway, it isn't so strange to defy convention and take a shot at changing things.
If Li Qishuo doesn't take his chance while the old man can still argue with everyone in Great Yan, then what was the point of transmigrating?
When Li Qishuo leads his army to retake the realm and arrives at Xuanwu Gate, he looks up at his old man standing atop the city wall and says:
"Retired Emperor! I've conquered the realm! What is the meaning of this?"