In total, by giving people $30 bonus, Intel lost almost 5 percent of productivity. That's a lot. Now, think about it. You give money because you think this would increase motivation. It actually decreases motivation.

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.

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.

If you think of people as making decisions actively, every time we think about the cup of coffee, we say, "How much will I enjoy the cup of coffee, what else could I not do in the future because I buy this cup of coffee?

We don't really want a huge house, but we want the house to be slightly bigger than our neighbors, and a car that is bigger than our neighbor's, and they're going on vacation that's slightly more expensive, and this escalation happens that things got out of hand.

When it comes to the mental world, when we design things like health care and retirement and stock markets, we somehow forget the idea that we are limited. I think that if we understood our cognitive limitations in the same way that we understand our physical limitations … we could design a better world.

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