An excerpt listing one of those motives:
(i) Sheer egoism. Desire to seem clever, to be talked about, to be remembered after death, to get your own back on the grown-ups who snubbed you in childhood, etc., etc. It is humbug to pretend this is not a motive, and a strong one. Writers share this characteristic with scientists, artists, politicians, lawyers, soldiers, successful businessmen—in short, with the whole top crust of humanity. The great mass of human beings are not acutely selfish. After the age of about thirty they almost abandon the sense of being individuals at all—and live chiefly for others, or are simply smothered under drudgery. But there is also the minority of gifted, willful people who are determined to live their own lives to the end, and writers belong in this class. Serious writers, I should say, are on the whole more vain and self-centered than journalists, though less interested in money.