Traders tend to purchase a long future contract in a bullish market. In case of a long futures contract, no matter how much did the price increase one will win the position.
Example of a bullish market:
Take the case of Bitcoin futures contract, one’s profit increases together as the market price of Bitcoin increases. The profit is the exact difference between the predefined futures price and the market price at expiration. The loss will, however, increase when the price sunk.