I would say it is our greed that is the problem, but is it really greed, or is the amount of over materialism something we subconsiously absorb in the littered with media advertising societies we live in.
As well as that, there is the social pressure to have what others have. I sometimes find us(me, my partner and my child) being labeled as poor, because we dont tend to buy what people around us typically spend their money on. We tend to focus more on quality of life, education, travel... If we were to give into the pressure that is very real, we would likely feel a need to not only have the education, travel, other stuff which is important to us, but also to have what is important to others, that would make us less ecentric. It would also make living twice as expensive or more, because not only would we then need for both of us to work full time, but we would also have the childcare and housekeeper expenses.