He's still laying you odds. He has to buy the bitcoins at today's price, and if he cashes out, he gets them at...well, half the price, since that's the terms of

He's still laying you odds. He has to buy the bitcoins at today's price, and if he cashes out, he gets them at...well, half the price, since that's the terms of winning. So he literally gets his money back. I think you should make the bet in dollars.