> There's a reason many ancient religions forbid loaning money at interest entirely; and it's the same reason we have bankruptcy laws.
The Catholic Church condemns usury as intrinsically evil because, in the words of Aquinas, usury is to "sell what does not exist". [1]
Aquinas observed that some goods are consumed by their very use, such as food or drink. Allowing someone to use such a good is equivalent to transferring the ownership. You cannot "rent" a sandwich or allow someone to "borrow" a bottle of wine, at least not if they intend to eat or drink it. Once the ownership is transferred, you have no basis to charge for its use.
He argued that money was an example of such a good. The only way to use money is to spend it, and it is consumed by that use. Therefore, loaning money at interest is an attempt to "rent" money that you no longer own, which is unjust.
Today, there is much greater access to profitable investment opportunities. It is even possible to obtain a guaranteed rate of return on money through CDs and GICs. It is therefore licit to reflect this in the "price" of money that is lent, but this is not usury. The Church cannot change her definitive teachings of faith and morals; usury has always been and will always be a grave sin. [2]
[1] https://www.newadvent.org/summa/3078.htm
[2] https://www.newadvent.org/cathen/15235c.htm