If I can buy a car today for $5000 and it is worth $10 000 in extra income next year to me because it enables me to get a job as a travelling salesman, should I take out a loan from Larry the Loan Shark at a 90% interest rate if no one else will give me a loan? Will I be better or worse off as a result of taking out this loan? Can you make a case for legalizing loan-sharking?