That’s actually how a lot of people got in trouble with these loans. It’s important to be disciplined and have a plan for paying down the principal. Again, think of somebody whose paycheck fluctuates. When they have a good month, they can make extra principal payments on the loan. Once the principal starts getting paid down, all future payments are adjusted based on the new lower balance. This drops the minimum payment or interest only payment going forward.
Here is an example of the monthly payment dropping after a principal payment.