He was a criminal lawyer, who became inspired to write thrillers, often loosely based on the cases he worked. Cool.
He's something of a legend in terms of success, selling his first novel from the trunk of his car, rocketing to Hollywood stardom, reserving spots on the bestseller list.
As usual, the best lies about self publishing have a kernel of truth: Grisham did sell a number of his own books from the trunk of his car - that bit is true.
What those 'self publishing success' lists fail to mention, is that the book wasn't self published.
Grisham's first novel, A Time to Kill, was published by Wynwood Press, a regional publisher, in 1988 - after shopping it around for a year. The initial run was a relatively modest 5,000 copies. Like many books, the entire print run didn't sell. But it was professionally edited, vetted, polished, and distributed.
Unlike most writers, Grisham could afford to buy the remaindered copies and sell them himself. Unlike clueless self and vanity publishers, he had a direct line to those people who would be interested in crime fiction - namely other lawyers, judges, law enforcement officials - y'know, the people he saw every day.
He also kept writing like mad. His next novel, The Firm, was purchased by Bantam/Doubleday and went on to be a bestseller in 1991. That's what got Hollywood's attention.
The first film made from his books was actually the unknown (at the time) A Time to Kill, and was produced in 1993.
No denying that it was a combination of luck and writing prowess that lifted him into household name territory - but self publishing had nothing at all to do with it. Nothing.