Utilize your financial knowledge, give your answer or opinion to the input question or subject . Answer format is not limited.

Why would anyone want to pay off their debts in a way other than “highest interest” first?
In some cases, it might be rational to pay low-interest debt first, because the consequences of defaulting on that debt are worse.   Consider this simplified example.  Suppose you have two debts: a low-interest mortgage, secured by your house, and a high-interest unsecured credit card debt, both of which are within a few years of being paid off.  There is a chance that sometime between now and then, something will happen to disrupt your income (e.g. medical problems), and it won't be possible to make the payments on either loan.   Defaulting on the credit card loan will result in a lower credit score and calls from collection agencies.  Defaulting on the mortgage will result in the foreclosure or forced sale of your house, at best forcing you to move, and at worst leaving you homeless, at a time when you are also facing other (e.g. medical) problems.  So you might rationally judge that losing your house is much worse than bad credit.  Therefore, you might rationally conclude that it would be better to direct extra income toward paying down the mortgage, to increase the chances that, if and when an income disruption might occur, the mortgage would already be paid off.  In other words, you shorten the window of time where income disruption results in foreclosure. You might decide that this increased security is worth the extra interest you will pay, compared to the strategy where you pay the high-interest loan first. This is a fairly special situation, but you asked "Why might it be a good idea to do this?", and I am just giving an example where it could rationally be considered a good idea.   (Of course, in a real-life version of this example, there might be other options available, such as refinancing the mortgage.  If you like, you could imagine a more extreme example where the lower-interest debt is owed to Joey Knuckles the loanshark, who will come and break your kneecaps if you miss a payment.)