I would guess the letters were written by middle- to affluent-income people. Why is it that when minorities and low-income groups complain about the unequal distribution of wealth those of moderate affluence always seem to react in a high moral tone. They say, "Quit whining. This is America. The sky is the limit. If you'd just get off your lazy duffs and work as hard, you too could be affluent."
Now these same people look a few rungs up the ladder at Griffin's life style and they again take a high moral tone. They cry "greed." I say "sour grapes." In this society the operative mode is "If you have it flaunt it." Whether it is wealth, talent, good looks, whatever. So my advice to those who criticize Griffin is, "Quit whining. This is America. The sky is the limit. If you work as hard as Griffin, you too can live on top of a mountain. Go for it."