A fortune can be a large amount of money, and fortune is a form of fate. So you want to have the good fortune to make a fortune during your career.
Fortuna was the Roman goddess of fate and luck. She was sometimes depicted with a wheel, and the random spinning of her "wheel of fortune" became a symbol for the unpredictability of fate (and, much later, the title of a popular game show). A fortune teller can look into her crystal ball or tarot cards and predict your future. But her predictions are probably about as accurate as the "prophecy" that comes inside your fortune cookie.