Insights:

1. Once we own things, we value them more.
2. The endowment effect can mean that objects have a claim on you, we perceive them to be more important than they are.
3. We can find it difficult to give up that which we own.
4. Accumulation is costly at any price.
5. Physical items that we own consume time, space and energy.

Principle:

1. Be cautious about the things you acquire, including free things.

Definition:

1. "The widespread psychological tendency to underestimate how long it will take to complete a task."