I dont know why, but normally they said they could hold the btc price for this contracft under 200$ and uz can still earn with this contract.
They have said that at the past but I think that is more to do with whatever difficulty level Bitcoin is at the time they write that rather than a promise that no matter what the difficulty level is at the future.
The last few difficulty rises have been huge compared to the last 6 months for example.
Just for reference.
At current difficulty, contracts on 0.0012 USD per GHs or 1.20 USD per THs, Bitcoin price would have to be at around 223 USD before zero payouts.
Contracts on 0.00099 USD per GHs or 0.99 USD per THs, Bitcoin price would have to be at around 185 USD before zero payouts.