Such costs are one reason that people don't come out of Medical School, Law School or graduate school and purchase a fast food franchise or a carpet cleaning business or buy their own taxi license or embark on any other similar venture. It would be nearly impossible for such people to earn economic profits. Their cost would be much higher than someone with, say, a high school education since their forgone income is so much greater. So, economic profit means revenue above all out-of-pocket expenses + best forgone opportunity, or economic profit = revenue - economic cost. If we remember this, many decisions people make become clearer.