Interesting idea. At first, I thought you could only lose money if you didn't accomplish your goals. But then I realized that money was being shared among the people who joined the same challenge. This mechanism not only disincentivizes not accomplishing your goals but also incentivizes accomplishing your goals.

Also curious about whether there is any form of verification of whether someone accomplished their goal. If not, this could result in bad actors trying to exploit the system by always checking their goals as completed. One potential way of getting rid of exploiters would be to remove the positive reward factor of the game, for example, the money lost by the participants could be sent into verified charity funds instead of being shared among the people who joined the pot.

I also have some doubts about the efficiency of mixing external motivations (in this case losing money or increasing a bit) with internal motivations (the goal itself). But this is another topic for discussion.

Anyway, this is a very interesting idea nonetheless. Good job! :)