Good that the OP hasn’t discovered commits.to yet, with no authentication and all
Nick Winter brought up #1.
See, the real cost of failing a goal is not the loss of your Beeminder pledge money. It’s the loss of confidence that you will meet all future goals that you perceive as similar to the current goal. You will trust yourself less. And because the motivation to pursue a goal is largely based on your confidence of success, that blow to your confidence will demotivate you, making you more likely to fail.
Ooooh perfect! This is exactly what I was looking for