Kurt Vonnegut sold Saab cars, and Harper Lee was a reservation clerk for Eastern Air Lines. J.D. Salinger worked as an entertainment director on a Swedish cruise liner. Charles Dickens labeled jars in a shoe polish factory, and was also a journalist.
Notably absent from the infographic is Hunter S Thompson, who worked as a security guard, caretaker, and was almost elected sheriff of Aspen, Co.
Speaking of Thompson, I think he would make a great start for an infographic on drugs consumed by famous writers. In his case, the answer would be "all of them".