A future, in most cases, is often like a bet. I promise to buy x amount of something within x time with the hope that what you paid now for it has gone up, while the seller sells it down (and therefore closes the purchase now at a higher price) . A struggle to see who is the smarter of the two, although it can also be used as insurance (so as not to be left empty). Futures contracts can also be made on interest rates (which reached the general public in the form of mortgage clips). In summary, although potentially profitable futures are potentially dangerous and that is one of the reasons why bitcoin has been affected.