"Can't afford uni" Is still a bullshit excuse, you don't have to pay it till after, and even then you barely pay it. Just do what you like.
I thought I could afford University, but it turns out I couldn't, and this was before the financial crisis hit.
I did an Undergraduate Degree in Pharmacology, then a PGCE in Primary Education, then a Masters degree in Primary Education. The latter two I did mostly off my own back.
My parents had to lend me about £2000 over the course of just my Pharmacology degree to help me make ends meet. I was working at that time too during evenings and 16 hours at the weekend. I was part of the 'means tested' group that meant that I wasn't flat out disadvantaged, but the level of loan I got from the Student Loan Company was nowhere near enough to get me through. That group exists.
My family is by no means wealthy either. We come from a poor area in Thurrock. The interesting thing is that I am rather frugal with money and resources - like my parents.
Students aren't short sighted. They look at the system as a whole - including their life prospects after the course. For example the housing market is not friendly to students, particularly students looking for a place of their own. Job prospects aren't that hot in most professions either.
Its not just about getting through the course, but living with the debt and the prospects of no job and an inability to move out that students factor in when declaring that they cannot afford University.
After finishing my three courses I was personally in £32,000 of debt to the government and then at about £2400 to my parents. Granted, my route through University is not common, but I doubt anyone would dare to take that route now that things have changed.