If the transaction doesn't immediately (within the same block) result in enough profit to pay back the loan with interest, the loan is canceled altogether, i.e.

If the transaction doesn't immediately (within the same block) result in enough profit to pay back the loan with interest, the loan is canceled altogether, i.e. basically it doesn't even happen. Then you only pay some gas fees for executing the smart contracts up to that point (which can be a few hundred bucks nowadays, I must say).