The MC is the second son of the first wife of the Baron. Since the father remarried to someone higher in the nobel hierarchy the son is being suppressed. The social standing of Women and Men is supposed to be reversed in this world with woman having multiple male lovers and so on.
Now it might just be me, but in our society there is no polygamist relationship where the men has multiple wives and would allow one of his wifes to stay married to her previous husband. If nobel men can't find a wife if they are over 20 years old, how did the MC's father find a second wife when he was clearly over 20? If woman are in dominant position in this society, why is the man the nobel? Shouldn't it be the woman? Shouldn't all the woman be the only ones in line to inherit a title? Why would the matriarch of the family spend money on a son (the father) who was sold to another woman? Shouldn't he be living with her and the woman of the barony be taking over?
As I stated the basis of the plot is a huge plot hole.
Example: He draws a rune on himself to hide his power. Later it wasn't himself who did it, it was his cousin who was jealous of his power and wanted to suppress him. Next he suddenly has a power to make people forget everything about him that they learned before meeting him. However it has affected none of the previous people who met him and already knew things about him like his entrance test score.
Chapter 41 closer to the end:
Today they would pry back with partners, all those materials would not be kept just in a few houses, wanted to speed up to rob in front of those people!
For example early on in the story he goes to a library to read cultivation manuals, the librarian is mad at him for just flipping through all the books and disrespecting the books and bans him from the library. Another student wants to show him up and starts asking questions about the books in the library. He answer everything spot on. This gives the other people the idea that he might have studied everything before. So to prove that he was not disrespecting the books but actually studying he goes and tells them where the book is located in the library and what page the solution is on. For someone who is trying to HIDE his skill this is like putting it on a advertisement board and going look at me, I can read thousands of books and know every word of it inside of a day.