The legal-marijuana industry in the United States could mint multiple billionaires in the next decade, a Colorado cannabis business mogul predicted Tuesday.

That explains why Tripp Keber, the mogul behind the Dixie Elixirs brand of cannabis-infused products, and dozens of other prospective investors crowded into a ballroom at the Denver Athletic Club on Tuesday to listen to investment pitches from numerous up-and-coming marijuana-related businesses.

The meeting of the ArcView Investor Network, a 3-year-old endeavor based in California, was the largest the group has ever held. Among the approximately 60 investors who attended the meeting were people already established in the marijuana business, like Keber, and also an increasing number of people from outside the industry who see it as a good bet.

Investment totals are expected to be announced Wednesday, but attendees said the figure could be in the millions.

“This is big, big business,” Keber said. “There has been an incredible amount of interest that’s been expressed to make investments in this industry.”

The meeting also represented a first for ArcView: The chance for investors to put money directly into businesses that handle marijuana. The investor network has previously plunged money only into the marijuana industry’s ancillary businesses — things such as security firms, cultivation-equipment suppliers and smoking-accessories manufacturers. Fear of prosecution by federal authorities — who might view marijuana investors as conspirators in a federally illegal conspiracy — kept the network from investing more directly.

But, with the newly announced change in federal law enforcement policy that provides state-law-abiding businesses more cover, the network is now looking to invest in licensed marijuana stores in places such as Colorado and Washington state.

The meeting saw pitches from a Denver medical-marijuana dispensary; a company that makes marijuana vaporizers that look roughly like cigars; the maker of machines that produce high-potency marijuana extracts; and the producer of a movie based on the life of a marijuana smuggler.

ArcView CEO Troy Dayton opened Tuesday’s meeting by declaring the cannabis business as “the next great American industry.”

But Steve DeAngelo, a California dispensary owner and a co-founder of ArcView, cautioned that the industry’s potential is dependent on business owners acting responsibly.

“Continued progress is going to depend a lot on how the country perceived us following through on our promises,” he said.