There is a lot of research from Paul Piff that you can Google. However, more recent research is a bit more nuanced and found that it has likely to do with a foc

There is a lot of research from Paul Piff that you can Google. However, more recent research is a bit more nuanced and found that it has likely to do with a focus on money, a bit further up the thread I linked to a BBC article which gives a good overview.