A very interesting premise, I look forward to seeing how the author carries it out. Brings up a number of questions like what really is misery, how are they using that data, and is the wish really worth the unhappiness it takes to get it? Like for these guys it sounds like with some effort they themselves could change their situation or outlook to be happier, so following the game I think they can make themselves unhappier than need be just for the prize.
I feel like this story may end up being a more elaborate "be careful what you wish for" or "grass is always greener on the other side" story. The characters will probably have to learn their friends have it harder than they realize and that they themselves have to power to decide if they want to be unhappy or happy.