In order to teach in Scotland she would need a postgraduate certificate of education (PGCE), requiring a full-time, year-long course of study. She began this course in August 1995 at the Moray House School of Education, at Edinburgh University, after completing her first novel
while having survived on social security.
http://en.wikipedia.org/wiki/JK_Rowling
Most people are going to find a way to contribute something to society even if they are
never capable of "supporting themselves."
The truth of any human community is that NOBODY ever truly supports themselves, we all build upon one another's accomplishments.
Even a wild man living like an animal in the forest isn't "supporting himself." He is supported by the natural environment, the air he breathes, the water he drinks, the plants and animals he eats.
In a vacuum an individual human dies. We could drop any "successful" person naked on Mars and they'd end up just as freeze dried and dead as anyone else.
Since our status in life is essentially random, because none of us chooses the circumstances of our own birth, everyone deserves those minimal things required to sustain human life, not just food, shelter, and medical care, but education too since humans are intellectual creatures and human societies are an intellectual creation.