Suppose you get a college scholarship so that tuition is free. the college education will increase your income by $400,000 over your lifetime. your other alternative is to work in a job after high school that pays $25,000 per year. room and board in both cases cost you $15,000 per year. compare the opportunity costs of the two situations.
If you work after high school, you will be giving up your college education as well as an extra $400,000 over your lifetime. If you go to college, you will miss the work experience after high school, as well as extra money in your pocket early on.