Kids don't care what party they have, right? They want cake and they want to run around. Nothing else matters. But in this escalation, all the kids want parties like their friends. So, if all the friends have an amazing, expensive party, they all want the same thing. If we all got to scale down as a coordinated effort, all the kids would have been just as happy.

Money is all about opportunity cost. Every time you spend on something, that's something you can't spend on something else.

Ownership is not limited to material things. It can also apply to points of view. Once we take ownership of an idea - whether it’s about politics or sports - what do we do? We love it perhaps more than we should. We prize it more than it is worth. And most frequently, we have trouble letting go of it because we can’t stand the idea of its loss. What are we left with then? An ideology - rigid and unyielding.

When we save, everybody in the household is just suffering. By having the coin in a visible way, when you scratch, you can say the person that is in charge of the making money for the family is doing the right thing.

Brands communicate in two directions: they help us tell other people something about ourselves, but they also help us form ideas about who we are.

If you want to spend more money in restaurants, use credit cards more than cash. If you want to spend less, use cash more than credit cards. But in general, we can think about how to use the pain of paying and how much of it do we want. And I think we have like a range. Credit cards have very little pain of paying, debit cards have a little bit more because you feel like today, at least it is coming out of your checking account, and cash has much more.

It was shocking to realize how many low-income Americans don't have savings accounts.