Change is hard, because people tend to overvalue what they have: what they already own or are already doing. Consider [a] ceramic mug: It’s off white, has a nice strong handle, and would be good for drinking any hot beverage of your choice. How much would you be willing to pay for such a mug? What’s the most you would pay to purchase it? When asked a similar question, people said they would pay a little less than $3 on average. It was a nice mug, fine enough, but nothing too valuable. A different group was asked a slightly different question. They were shown the same mug, but rather than being asked about their willingness to buy the mug, they took a seller’s perspective… Sellers on average wanted more than twice as much to part with the mug. Or a little over $7… it turns out that once we have something, once we’re endowed with it, we start to become attached to it. And consequently we value it more.

Jonah Berger's a world renowned expert on behavior change, social influence, word of mouth, and why products, ideas, and behaviors catch on.