Is a top MCAT score (515+) more due to luck instead of hardwork?

I've been working very hard to take my MCAT soon, but lately SDN has been scaring me. People here make it seem like a top MCAT score is more due to luck and that it cannot be guaranteed. I am shooting for a 515+ on the exam, and let's say that by the time I take it, I will have:

1. understood the concepts so well that I can teach it to others (frequent review of flashcards)
2. taken 6-10 practice tests and gone over very carefully
3. done a ton of practice passages, FSQ's (~3 hrs. a day...

Is a top MCAT score (515+) more due to luck instead of hardwork?

Is a top MCAT score (515+) more due to luck instead of hardwork?