"Area 51 Basecamp" organizer Keith Wright said that after drawing just 500 attendees at a Friday concert and vendors event planned for 5,000 at the Alien Research Center souvenir shop in Hiko, he had to pull the plug.
"We put on a safe event for the people that showed up," Wright said. "But we had to make the decision today because it costs tens of thousands of dollars to staff each day."
"It was a gamble financially," he said. "We lost."
Several dozen campers are still booked until Sunday, he added.
In Rachel, Little A'Le'Inn owner Connie West said she was sad to hear the Hiko festival didn't succeed.
West, in a voice hoarse from stress and lack of sleep, said a noon-to-midnight slate of "Alienstock" musical entertainment will continue for the several thousand revelers camping on her property and nearby federal land.
"This is the most fabulous time," West said. "I'm just so grateful that people came. This is their event as much as it is mine."
Lincoln County Sheriff Kerry Lee called activities "pretty calm" early Saturday in Rachel and Hiko.
Emergency services chief Eric Holt said the number of law enforcement officers and medics were being scaled back, but that officials weren't becoming complacent.
He said resources mustered from around the state to handle up to 30,000 people probably won't be needed for the estimated 3,000 campers and festival-goers at "Alienstock" in Rachel.
"The best-case scenario is pretty much what happened," Holt said.
In Nye County, Sheriff Sharon Wehrly reported no one showed up early Saturday at a main entrance and an auxiliary gate at the once-secret Area 51 U.S. Air Force facility.
Wehrly revised to 100 each the number of people who appeared at each of those gates early Friday near Amargosa Valley, a 90-minute drive west of Las Vegas.
Lee and Holt, about a two-hour drive north of Las Vegas, said revelers gathered until about 4 a.m. at two gates between Hiko and Rachel.
The sheriff said about 20 people broke from among revelers and "acted like they were going to storm but stopped short."
Lee reported one arrest, for disorderly conduct, at the end of the "Area 51 Basecamp" concert in Hiko. That brought the number of arrests since Thursday to seven - all misdemeanors and most for trespassing.
Holt said one man was treated for dehydration by festival medics in Rachel, and a man reported missing Friday morning after heading Thursday from a festival campground in Hiko toward an Area 51 gate was found safe Friday evening. He said he didn't have any other details.
Two crashes were reported involving vehicles hitting cows, Holt said. Motorists weren't injured. Officials noted the highway between Hiko and Rachel is open range for cattle grazing.
The vibe among the assembled humans, which Lee estimated totaled in the low thousands, remained mostly harmless.
While costumed space aliens were a common and sometimes hilarious sight in events that began Thursday, no one has reported seeing actual extraterrestrials or UFOs.