Many of them can do as I did and go straight from high school to the work force. Others can go into apprenticeships in the skilled trades. Still more to community and vocational colleges to learn business management or accounting.
The fastest growing profession for 4-year college graduates is "HR professional". Come on. You don't need a college degree to be an HR rep, or to be a sales account manager, or to work in a purchasing department. That's something like 60% of the white collar jobs in a typical corporation, which we pretend that you need to spend $150,000 on a Russian Lit degree to competently execute.