Oil watchers are eyeing a potential freeze by producers as the next catalyst for the commodity, but one oil bear says crude's biggest obstacle is already here.

"I think Uber is a threat to oil for the simple reason that millennials have embraced it dramatically," Dennis Gartman, editor of The Gartman Letter, told CNBC's "Fast Money" traders on Monday. "The millennials are saying 'I really don't need an automobile.'"

Since the founding of Uber in 2009, the ride-hailing company has launched in more than 400 cities and taken passengers on more than 1 billion rides, according to the company's website. And it's the simplicity and convenience of the service itself that Gartman said has converted many would-be personal vehicle owners into Uber-dependent passengers. Oil has fallen more than 40 percent since Uber's inception.

This theory, he said, can be illustrated by taking a look at the history of U.S. total vehicle miles traveled, as reported by the Federal Reserve Bank of St. Louis.

"If you take a look at the average amount of driving that has taken place in the United States, it was a very well-defined trend line. We have broken that trend line dramatically," said Gartman. "That whole mystique of driving an automobile is lost and it's not coming back."

For Gartman, the ride-hailing company diminishes the demand for gasoline as well as automobiles — a bearish implication for ever-increasing oil production.

"I think on balance that is a terribly bearish circumstance," said Gartman.

The CNBC contributor stands by his theory that oil will continue to trade between $32 and $42 for the foreseeable future. In a "Fast Money" interview last month, the so-called Commodities King said he would not see .

"I think $42 is going to be very difficult to get through," said Gartman. "There are so many wells that have been capped that could be brought online very quickly."