The open interest on Bitcoin (BTC) Dec. 31 call options between $100,000 and $300,000 reached an impressive 6,700 contracts, which is currently worth $385 million. These derivatives give the buyer the right to acquire Bitcoin for a fixed price, while the seller is obliged to honor the price. One might think that this is a great way to leverage a long position, but it comes at a cost and is usually quite high. For this right, the buyer pays an upfront fee (premium) to the call option seller. For example,…