The Daily Beast has an article Consumption Makes Us Sad? Science Says We Can Be Happy With Less by Barry Schwartz (author of The Paradox of Choice) that serves as a nice compilation of various psychological and behavioral economics findings about money and happiness.
The first main topic is hedonic adaption. When things are awesome, we eventually get used to it (celebrities, lottery winners). When things are really awful, we tend to get used to that as well (disabled persons). This is why it’s hard for people to achieve a constantly higher level of happiness. We get a nicer car/house/toy, we get used it, and then soon we want an even nicer car/house/toy, never getting anywhere as if we are walking on a treadmill.
Simply knowing that the good feeling from that purchase is only temporary may help you cut back on your spending. In addition, author Dan Ariely suggests you deal with the hedonic treadmill by pacing yourself when it comes to experiencing pleasure, and (when needed) making painful cuts all at once. For example, you might not buy a entire home theater setup all at once, but perhaps upgrade one component and wait until the shine completely wears off before buying a new couch. If you need to cut costs, it may be better to make a big spending cut by downsizing your house rather than cutting things you’ll miss repeatedly like your daily coffee or selling your stuff on eBay piece-by-piece.
The second main topic is how most of us get more pleasure out of doing stuff than out of having stuff. This especially applies to activities with other people and/or activities that we find important and worthwhile. A nice result form this is that those activities often cost very little or nothing. I think this concept is related to the research by Daniel Kahneman that found that happiness did not increase past earning $60,000 a year.
Below 60,000 dollars a year, people are unhappy, and they get progressively unhappier the poorer they get. Above that, we get an absolutely flat line. I mean I’ve rarely seen lines so flat. [...] Clearly money does not buy you experiential happiness, but lack of money certainly buys you misery,” he said. But the real trick, Kahneman said, is to spend time with people you like.
We all need a certain amount of “stuff” (and thus money) to make us feel physically healthy and safe from harm. Past that, adding more stuff doesn’t seem to help. Schwartz suggests that at some point, one might even stop looking for a job that pays more, but instead go for a job that makes us feel valued and doing something important. Of course, more money can get you to early retirement faster if you’re into that sort of thing, so there is a balance to be made.