I didn't say there isn't a diminishing value of each dollar, but your comment seemed to imply that at a certain point, people will be "content" at a certain income level and not try to get more money.
Rich people are a counterpoint because there are people with incomes the size of a small country, and they are still striving for money. Given the diminishing utility of familiar pleasures, I think its likely that constantly reaching for "more" is the norm, rather than the exception.
