So this dovetails with what I think is the most fascinating topic in evolution: the demographic transition in humans. If you're not familiar, demographic transition is the term used to describe what has happened to the demography of nations as they become developed. Which is that, rather than producing more children with their material abundance, people in rich nations have less children. This is not, at all, what biology would predict. More resources should lead to more offspring.
My personal hunch as to what causes the demographic transition is that we have an evolved system for determining whether we are doing well or doing poorly and that system calibrates itself by examining the people around us. But, because our current economic and social system sorts people by income and status (talented people migrated into the cities from farms, even more talented people moved into more expensive neighborhoods, etc.), and because advertising constantly shows us higher levels of consumption to aspire to, even people who are, in an absolute sense, raking in obscene amounts of money are surrounded by a peer group that are roughly at their level. So it never really feels like you're rich; even though you live in a $3 million dollar home, you live on a street with $8 million dollar homes; even though your kid goes to a $30k/year private school, you can't afford to spend $200k vacationing in France during the summer like some of their peers, etc.
Interestingly, this parallels my own experience. As a senior developer, I'm now making roughly 3x what I made before becoming a programmer. Back then I would have imagined that all of my wants would be satisfied by 3xing my income. Yet somehow I still yearn to make more.