Schelling Point/Focus Point

In this topic, we consider, why miners and other blockchain nodes stick to a given protocol instead of following their own rules.

Imagine the following experiment. A game master asks each group member to pick a box from a given set of boxes. You can see the boxes in the figure below. If every group member picks the same box, each participant receives a reward. But if even one member picks another box, nobody receives anything.

The challenge here is that the group members are not allowed to communicate. What box would you choose in this case?

Well, there is one box sticking out of the crowd. Box number three has a different color than all the other boxes. Your rationale could be: If I chose a random box and everybody else does the same, the likelihood that we all pick the same one accidentally is very low. But if I take the blue one, I can hope that others might think the same way and chose the blue one too. In our case, the blue box is the focus point, also called the Schelling point.