Obviously most people plan to be in a situation better than they currently are or they plan to do their job well and be there for however long they can without getting laid off for one reason or another, if your answer is overly ambitious they can take that as a signal that you are too competitive(lack loyalty) and will leave the company if you don't rise fast enough, if your answer to underwhelming you are viewed as complacent and uncompetitive maybe even lazy.