Traders have alighted on what some believe to be a one-way bet in the world’s most important commodity market: oil prices going to $100 a barrel. They have scooped up call options tied to Brent and West Texas Intermediate crude-oil prices reaching $100 by the end of next year. Oil prices haven’t topped that milestone since 2014, when a gush of U.S. crude depressed energy markets.

Owners of $100 options—now the most widely owned WTI call contracts on the New York Mercantile Exchange—are making a leveraged bet that oil prices will hurtle higher after already surging more than 40% this year. The roaring rally, goosed by thawing coronavirus restrictions, has lifted WTI prices to their highest level since 2018 at almost $70 a barrel and average U.S. gasoline prices above $3 a gallon, according to GasBuddy. The popularity of $100 options is another example of traders converging on seemingly outlandish wagers they consider to be almost guaranteed ways of making money. Analysts say oil is unlikely to zip to $100 any time soon because the world economy is still recovering from the shock of Covid-19 and major producers are lifting output in response to resurgent demand.

“Everyone’s been looking at it,” Adam Webb, chief investment officer of trading firm Blue Creek Capital Management LLC, said of $100 call options for oil delivered in December 2022. “It’s a no-brainer.”

Mr. Webb thinks the rebound in the U.S. economy will help to catapult WTI prices toward $100 a barrel. The fund has sold put options to fund the purchase of $100 calls, which he judges to be unsustainably cheap.

The flurry of activity in $100-oil options holds parallels with speculative wagers that have proliferated in other corners of financial markets. In January, traders piled into options on unprofitable companies such as GameStop Corp. and AMC Entertainment Holdings Inc. They figured doing so would boost share prices, inflict losses on bearish investors and prompt them to buy back shares they had sold short. The self-fueling dynamic drove prices even higher in a trading frenzy that reignited in early June.