Why might a person not receive what they hope for despite taking the necessary means, while others achieve their desires without expending the same effort?

"Taking means [expending effort] along with reliance upon Allah is important for achieving one's goals, for Allah is the One Who makes the means effective. What you mentioned about others not taking means and yet achieving their goals is contrary to reality. Perhaps their good studying coincided with the exam questions, or perhaps you are not fully aware of their efforts. You might also have shortcomings in your study methods or concentration. Therefore, we advise you to draw closer to Allah Almighty, strive in His worship and supplication, rely upon Him, and be content with His decree. Then, endeavor to identify the true reasons for your setbacks and address them."