Saccade,
Interest is currently 7.5%. About £3,000 accrues during the course and another £2,000 if you take the six month repayment holiday.
£76,855 + £5,000 = £81,855 not the £90,475 you state. If you meant the £90,475 as the total, then you are way under. If you take 11 years to repay, it will come to about £30K total interest.
The interest is not part of the price of the ATPL, it is the cost of the money that let's you do the ATPL now so you don't have to wait another 10 years while you save it up.
How much more could you earn working as a pilot for those 10 years instead of what you do now? You could be earning £100K with Ryanair as a Captain in 5-6 years.
I am not advocating taking foolish risks, but there are people who could make the £600 per month payment on what they earn today quite handily and they are doing the maths and deciding the risk is worth taking for the opportunity of an extra 10 years earning pilot wages.
Many are doing the maths and deciding Modular is a great way to get there for even less. It's horses for courses, but without the risk, there is no reward.