I was going to be a video game animator, I dedicated four years of my college life to it, and went in obscene student debt, literally they wanted a house payment a month to repay. The problem was that about two years into it I discovered the details about my dream career and decided that I would be sacrificing too much, 60-80 hours a week would murder my family life. The decision to stay in school became more a default, no longer a dream.
Look at Wu Minxia, a young Chinese diver who was taken from her family and trained day in and day out to dive. Sure she got the gold for the third time, but at what cost? Not knowing her family, not knowing her mother was battling cancer or that her grandparents had died! We'll never know if it was her dream originally or if it was the dream of her family and government, but she was dedicated and she did work hard.