Okay, what about currency futures then? Should I explain to you the purpose of them (it will be the same for bitcoin, and even more for bitcoin, for that matter, lol)?
Currency futures exist and are popular. They are popular exactly because central banks can print as much fiat as they want and banks can receive that fiat at low cost and do all kinds of funny business with them on big leverage. This has limited application to bitcoin.
Please, be concise. Bitcoin futures would exist just for the same reasons that currency futures and commodity futures exist. The primary aim of futures is hedging against price volatility whether it is currency or commodity. And yes, there are even futures for commodities that don't even exist yet (consider crops)...