Author's note:- many readers have doubts so I would like to clear some points.
1. MC doesn't know that he is from a novel series. there were all the shows and movies in his original world except the Harry Potter franchise. All the information about future events he know is because of kaleidoscope. Kaleidoscope magic's one of the primarily function to gaze into parallel worlds and Gilderoy uses the same to look into the parallel timelines of his world to know the general trajectory of his world. And that's also why he is a little skeptical about everything even after knowing the future, because every timeline is slightly or heavily different from one another.He knows what will happen but he knows the future is not bound so he will often take action even when according to the plot he didn't need to all because he wants to be on the safe side.
2. Many readers are complaining about why MC is acting like an idiot so I would like to say that the original gilderoy Lockhart was also an idiot. MC knows that anything is possible in a place like the wizarding world, so someone killing Lockhart and impersonating him isn't out of question. so that's why he is behaving like the original so as to not draw any suspicion. and also MC realized that Gilderoy Lockhart gained himself quite a reputation by his behavior so doesn't think there is any need to change it.
3. Many readers also complained about why MC showing things that will draw attention to him if he doesn't want to end on dumbledore's suspicious person list. The answer is simple because he has ambition. Original Gilderoy didn't inherit anything from his parents. His father was a muggle-born but even then he somehow built himself a reputation, especially in a world where nobility and stuff like pureblood still exist. the MC has even greater ambition than the original Lockhart and his only advantage is his cheat-skills which he plans to use to the fullest even if he might end up on the bad side of some really powerful people.