I dont know or they run out of hashpower and they want to earn more for the last hashpower.
I mean a lot of People wanna buy hashpower there and Demand determines the Price..
doesn't make sense, people won't invest at this levels, if bitcoin drops and go stagnant, contracts will expire, without profit to buy more hashpower. if bitcoin breaks all-time highs, all is fine, place your bets, no refunds LOL