In contrast, if you are “going short” on Bitcoin, you assume that Bitcoin prices will fall. Buying put options will enable you to sell Bitcoin at some point in the future at a price that is higher than the future price you expect. In analogy to the example above, if the current Bitcoin price is 5,000 USD and you expect it to fall to 2,000 USD in 6 months, then put options allowing you to sell Bitcoin for 5,000 USD in 5 months (when everyone else is selling for 2000 USD) are very valuable.
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.