Other psychic factors being equal, it is to everyone's self-interest to maximize his monetary income on the market. But this maximum income can then be used for either “selfish” or for “altruistic” ends.
After quoting H.L. Mencken’s famous quip, “Nobody ever went broke underestimating the intelligence of the American people,” Andrews wonders, “I don’t know if old H.L. was a bookmaker, but he would have been a great one if he had been.”