Nobody is lucky or unlucky and it is hard 90:10 equation that is first it is hard work and later luck if one may count based on hard work.
Forget luck in competition. You have to ensure that for MBA entrance exams, you are well planned to prepare and this plan is well executed to get admission only and not less than that.
Time is over and luck stories are of passé. A new phenomenon is success stories based on hard work. Competitive skills are order of the day and others will be left in race.
To gain confidence and to be believer only in hard work and not in luck, one needs will power to inculcate winning attitude and new DNA of becoming go getter has to be transformed.