Create a bitasset that can only be created by placing one BitUSD in collateral.
No margin calls are possible because the maximum outcome is 1 USD and the min outcome is 0 USD.
At the end of the match, the issuer will trigger a "black swan" at a price of either 1 or 0 USD. If you win you get $1 if you lose you get 0.
If you buy at $0.1 and win, then you get a 10x return. If you buy at $0.50 and win you get a 2x return. If you buy at $0.90 and win you get a 11% return. Likewise, if you sell at $0.1 and it goes to 0 then you make $0.1.