Sam's Thought Process:
- If John stays silent:
- Better for Sam to betray (Sam's reward: 0)
- Than for Sam to stay silent (Sam's reward: -1)
- If John betrays:
- Better for Sam to betray (Sam's reward: -2)
- Than for Sam to stay silent (Sam's reward: -3)
Conclusion: It only makes sense for Sam to betray. John thinks the same way.