In "Kidnapped" by Robert Louis Stevenson, why did David leave Essendean?

David leaves Essendean after his father's death.

“Are ye sorry to leave Essendean?” said he, after awhile.

“Why, sir,” said I, “if I knew where I was going, or what was likely to become of me, I would tell you candidly. Essendean is a good place indeed, and I have been very happy there; but then I have never been anywhere else. My father and mother, since they are both dead, I shall be no nearer to in Essendean than in the Kingdom of Hungary, and, to speak truth, if I thought I had a chance to better myself where I was going I would go with a good will.”