You could profit off a long term loan if you find a legitimate investment that pays out more than the interest the loan is charging you. Free monies ^_^
Long term loan is risky due to the high volatile price. You may get busted. Besides that, what is called a legitimate investment is hard to identify. The business can turn to scam in any time.
I'd say that it is useful to borrow bitcoins if you need to buy something quickly, like if there's a discount on an object with a countdown, and if you won't be able to have the money needed before the end of the countdown.
Why not keep some bitcoin for yourself? The bitcoin lenders normally charges higher interest rate than fiat money, like 10% or more. What is the point of being hurry and paying more rather than having plan well. It will safe you a lot of money.