Responses

I totally agree with you. Its like when your so obsessed with proving someone wrong, and its especially hard if its a close person like his father. I think in a situation like that a person doesn't care about how other people feel or how he treats them, its like being totally hypnotized and focused on that ONE thing. But now that he heard that there could be other things in life than just proving his father wrong, he might realize and overcome his trauma.
After rereading it, I've formed a new opinion about the jinx. I saw a lot of readers have been disappointed in the jinx because its so much more simple than we expected.
But after rereading it from JJK's POV, that might be the point. Jinx is the starting point of the story and the word itself implies something supernatural, but JJK's jinx here is as simple as someone getting a full night of sleep before an exam. But i think the simplicity combined with JJK's obsessive adherence to it is the point.
Because of his difficult past and inherently prideful nature, he has a very deep emotional dependence on success and he'll cling to anything that will boost his chances. His whole routine of cologne, milk and sex are technically all part of his 'jinx'. He clings to this idea of a jinx bc it brings him comfort that he'll succeed the next competiton.
In many ways, this is very in-character with JJK, to obsess over even the little simple details. Yes we as readers expected more, but I think it adds to JJK's character how manic he can get into the little things as long as it contributes to his performance. He jumps very quickly to the idea of a jinx. I wasn't a big fan of the origin story at first but after rereading it, I do think it adds layers to JJK's character. He's not just obsessive and OCD about his routines but he's desperate to find his footing.