> But recent research indicates that when people get some money—a bonus, a tax refund, a small inheritance—they are, in fact, more likely to spend it than to save it.

Not recent at all. I first read about it in The Millionaire Next Door book. Referred to as the "better than" theory [1].

Plain and simple, people don't like to save when they have the option. They like immediate reward. If you make $500 more a month after a raise, many people will reward themselves for the raise, justify buying something they've wanted, etc. After a while, the mindset that they are living just fine while spending the extra money sets in and they end up never saving the extra $500.

[1] https://en.wikipedia.org/wiki/The_Millionaire_Next_Door#.22B...