Why am I doing these courses

Well this is along story, I came to New Zealand to study medicine and be a dentist but I had so many difficulties in getting an offer of placement at the University of Otago which was my first destination in New Zealand. However after I gave up from the Dentistry stream I decided to do a bachelor in Commerce. I moved to Christchurch and I enrolled with the University of Canterbury. My older brother Mohammed who has already done his master degree in Commerce has helped a lot with choosing the suitable subjects for me. However I still want to be a dentist.