This is key.
No one has ever said "I'm going to stop making money because I have $1."
No one has ever said "I'm going to stop making money because I have $1."
At $1 the second dollar is useful, at $50,000, I'm good for the year and will not pursue additional dollars. Replace $50,000 with whatever amount you need to feel content.
I continue to work because I genuinely enjoy what I do.
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.