How can academic success be achieved after expending great effort, and can arrogance be a reason for lack of success, bearing in mind commitment to worship and good morals?

The low grade in the exam is Allah's decree and destiny, which must be accepted. As for the effect of sins on what happened, its knowledge is with Allah Almighty, even though the ill effects of sin and hastened punishment in this world are a reality. To achieve success, seek help from Allah and rely upon Him, exert effort, and abandon obsessive thoughts, for whoever strives will find success. Beware of arrogance, for it is a cause of defeat.