The rich are different from you and me, though maybe not quite like we think they are. We imagine athletes, entertainers and, more recently, entrepreneurs, when we ponder the wealthy. But the enduring lesson of the classic personal finance book, “The Millionaire Next Door,” is this: Most of the rich grow wealthy because of modesty, thrift and prudence. They live happily in starter homes. They don’t subsidize irresponsible adult children. They have an allergy to luxury automobiles.