Oh, you mean to start repayments.
Sure, they'll repay some of it. But a huge amount will get written off after 30 years.
It's not just the amount, it's the compound interest.
I went to university almost 20 years ago, when the maximum maintenance loan was just over 3k a year. In my second and third year they introduced an extra loan for the tuition fees, which were then around 1200 a year. So the amount I initially borrowed was about 11k in total. Now I went to university before the financial crash, when the base rate was around 5%, and graduated around the time of the crash when the base rate fell to zero.
The loan starts accruing interest as soon as it is paid, so I started accruing interest on the first 1k or so in Freshers' Week, even though it would end up being another 6 years before I got my first pay cheque. Unlike many people, my starting salary was well above the repayment threshold.
By the time I graduated my student debt was around 13k, of which 11k was the original loan and 2k was interest. Most of that interest was accrued in the first couple of years when the base rate was still high. But then after I graduated, during the financial crash, I paid almost no interest at all, and one year literally no interest, because the base rate had fallen to 0. I then started working at 25 and had paid the whole lot off by the time I was 31.
Someone who started university between 2006 and 2011 will have paid about 3k a year in tuition fees, meaning that for a three year course they would have borrowed around 6k more than someone who started university in 2005 or before.
Someone who started university post 2012 will have paid 12k in tuition fees, which is literally ten times what I paid a few years previously. And that's before you factor in the maintenance loan. Once you factor in the maintenance loan, you have borrowings of over 15k per year, so over 45k for a 3 year course and over 60k for a four year course.
BUT the interest rates also changed. So someone who started university in 2012 was paying, if I remember correctly, 6% interest. Starting in Freshers Week. This was at a time when base rates were still hovering around zero, so the amount of interest they were paying was considerably higher than wealthy adults were paying on their mortgages, probably equivalent to a reasonable commercial loan, and only about half the rate I pay on my credit card.
If you combine total borrowings of 50-60k with 6% interest, and people not even beginning to pay back even a small amount until they exceed the earnings threshold, which may be quite a few years after graduation, that's how you end up with amounts that most people are never going to pay off.
Someone whose salary maxes out at around 35k might conceivably spend 20 years making repayments and then still end up owing more than they originally borrowed after 30 years when the remaining loan is written off at the taxpayer's expense.
All of this is quite apart from the fact that the maintenance loan barely touches the sides of the actual cost of living these days, leaving students and their parents to fund a shortfall of thousands of pounds a year.