The best work in literature is always done by those who do not depend on it for their daily bread and the highest form of literature, Poetry, brings no wealth to the singer.
The greatness of literature cannot be determined solely by literary standards though we must remember that whether it is literature or not can be determined only by literary standards.
Literature deserves its prestige for one reason above all others - because it's a tool to help us live and die with a little bit more wisdom, goodness, and sanity.