If you don't solve the puzzle your money is gone. That's how site owner make money.
Actually, that's not true. In the very rare cases when a picture was not solved, the remaining money in the pot is transfered to the starting pot of the next challenge. This is stated in my ToS/Fees I believe.
But when someone know your puzzle you got others btc who put wrong answers, right?
Not exactly.
For each challenge I put from my wallet a starting pot.
People have to bet to place answers.
About 60% of their bet goes to the pot, the other 40% goes to my wallet.
When someone gets the answer right, the whole pot (the starting pot + those 60% of each bet places till then) gets sent to the winner.
Also the starting pot is 4 times the bet.
So to math it up:
B = bet
S = starting pot
S=4*B
After X bets my earnings are:
X*B*40%
And I've already paid for the starting pot:
4*B
So to break even for a picture I need:
X*B*40%=4*B
X*40%=4
X*0.4=4
X=4/0.4
X=10
I need 10 bets to be placed just to get back my money that I lost for the starting pot.
For each bet after the 10th, i'm making a profit.
Of course there are a few more factors that you need to take into account but they are trivial. For example I give out 5% of my earnings to the referral of the winner. So I don't get to keep exactly 40% of the bets. But on the other hand I earn some money from ads etc. And I also loose some money for the domain and the certificate so I guess it's quite more complex but in any case I consider 10 bets to be my break even point. :-)
You can read the ToS, Fees and the other help sections if you'd like to learn more. Or just ask of course.