In fact, as long as you analyze it carefully, you will know that Cao Shuang didn't completely lose the condition of being in danger at that time and didn't have no choice but to surrender. If Cao Shuang had listened to Huan Fan's advice and fled to Xuchang to organize military forces to conquer Sima Yi, he would surely succeed. Why do you say that?
First, although Sima Yi controlled the capital and the emperor Cao Fang, Cao Fang was no longer a child at that time, but was 17 years old. What does this mean? He is already a young man with ideas and opinions. Maybe today, people of this age are still immature, but in ancient times, they were basically married, so on the whole, their thoughts matured earlier, not to mention that Cao Fang was born in the royal family.
Therefore, it is relatively difficult for Sima Yi to control such an emperor. In addition, Sima Yi's coup was a misnomer. He is equivalent to a traitor and a thief. As long as Cao Shuang is in the name of destroying the rebels, dispatch troops calls on the soldiers of the whole country to rise up and attack.
Secondly, Huan Fan's proposal of going south to Xuchang is feasible. Because Xuchang was once the capital city established by Cao Cao, it has developed well in all aspects, and can provide sufficient salary and financial support, plus Xuchang has sufficient weapons and equipment. Taking Xuchang as the base area is completely feasible. Besides, don't forget Huan Fan's position at that time. He is a senior farmer and is responsible for the financial resources of the whole state of Wei. So with Huan Fan here, we can effectively guarantee the expenses and materials needed for the army.
Third, after the rise of Cao Shuang, most people in the Cao Wei court will stand on his side, because many of them are loyal to Cao Shi Group, so when Sima Yi wants to usurp the throne illegally, they really don't want to see Cao Shi's regime fall into his hands. Especially the nobles in Cao Shi, no one wants the family group to be usurped by outsiders, so they will unite against Sima Yi.
Plus Xia Houxuan is commanding the military forces in Guanzhong. If Cao Shuang is willing to fight back against Sima Yi, then Xia Houxuan will definitely support Cao Shuang. In addition, other military forces can be assembled against Sima Yi. Besides, when Shu and Soochow were still there, Sima Yi wanted to realize his ambition, but he also had concerns in this regard. So as long as the plan is reasonable, there is still a great chance to defeat Sima Yi.
It's a pity that Cao Shuang has no vision and no fighting spirit. He is just a man who longs for a rich life. Therefore, under the bait thrown by Sima Yi to protect his wealth and worry-free, he naively chose to believe that such a person could not lose his life.