Principal Artist at Zynga
San Francisco, California
Careers these days don't have to be the one thing that you do for your entire life. People grow and change over the course of their lives and that may include changes in career as well.
Speaking from experience I can tell you that doing a number of different things can help to give you a good, broad view of the world. I studied biology at UC Berkeley, went on to work in IT management for several years, got my master of fine arts degree, and have now worked in the video games industry as an artist for almost a decade.
I don't consider my education or other jobs as a waste of time. I learned so much more doing all of those other things than if I had only ever done art. That's not to say that knowing what you want and going after it whole-heartedly is wrong either. Just know that there's nothing wrong with changing your mind down the road.