The introduction of futures didn't lead to a wave of hedge-fund money shorting bitcoin. It led to retail and institutional money going long bitcoin. We talked last week about the spread between Cboe's bitcoin futures price and the actual price of bitcoin, which was wider than $1,000 for a while. The spread has tightened considerably -- as of 8:15 a.m. today, the CME futures traded at $18,585, Cboe futures at $18,670, and spot bitcoin at about $18,245, for a spread of about 2 percent -- but it still exists. Why would you pay more for a synthetic bitcoin in a month than you would for an actual bitcoin today? The answer, presumably, is that the synthetic bitcoin is more valuable to you: You want bitcoin exposure, but you'd prefer to get it through a standardized contract on a regulated exchange that settles in dollars. 
There's a lot of ins and outs which can get confusing in arbitrage trading. We won't go into the technicals of why futures contracts trade at a premium to spot price. You can read a full explanation here. If it's not of interest to you, all you need to know is that there's a tendency, the further out in time the futures contract expires, for the premium to spot to be higher and higher in nominal percentage terms.