It's the difference between comfortably affording mortgage repayments and it being a bit on the tight side.
If you hadn't gone to University and gained your degree, would you be earning the same amount of money as you are now, or less?
If you would be earning the same amount anyway, then University (and the loan) probably wasn't the right decision for you. If you would be earning less, then you should have a net gain or at least be breaking even.