So let me get this straight: the person is a means-tested dependent, but not when it comes to disable 16-year-olds being moved onto PIP or low income families continuing to receive tax credits and child benefit for them or 18-year-olds receiving 'child' support from their non-resident parent? How very . . . backwards, punitive and out-dated.
There also seems to be a real resistance to students working whilst studying, a lot of 'they can't possibly'. It's a really dated concept to have, very backwards as well and sadly, your system is really behind because in some places, N. America, for example (I'm from Canada), higher education is in large part set up for mature students and working people, even these so-called vocational degrees. It's not at all unheard for people who work FT and have families to also be studying for undergrad and higher degrees.
Really hope to see some progression in things but, given attitudes and Brexit, can't see it all changing or anything besides brain drain.
Some young people blow money and earnings, are lazy, won't listen to advice on money, are manipulative, too, so YABU because you don't know the whole story.