Opportunity Cost. When you use your money to pay off your home equity loan, you can't use it to do anything else. The cost of this is a little harder to calculate, because you're projecting what you'd do with the money in the future.pportunity Cost. When you use your money to pay off your home equity loan, you can't use it to do anything else. The cost of this is a little harder to calculate, because you're projecting what you'd do with the money in the future.