On February 23, 2013, 13,000 mixed martial arts fans streamed into the Anaheim Honda Arena, buzzing about feminism. They’d come to see the first women’s fight in the UFC’s 20-year history—just two years after UFC president Dana White vowed to “never” allow women into the Octagon, he’d agreed to put two women at the top of the night’s bill. Outside the arena, burly spectators discussed the sport’s civil rights moment in between play punches. Female fans came out in full force: One woman, standing in line for the bathroom, told me that she’d never before had to wait to pee at an MMA event.

The fans had come to see UFC history in the making, but they’d really come to see breakout star Ronda Rousey, the Olympic judo bronze medalist turned MMA powerhouse, and the woman who’d convinced White to change his mind. Her eventual win that night—Rousey caught competitor Liz Carmouche in her signature punishing armbar and forced her to tap out in the first round—was a foregone conclusion. And by the time the fight ended, the enthusiasm around a new era of female Ultimate Fighting Champions had already begun to dim. “I’d say it didn’t disappoint,” UncutSports commentator George Bedford said. “But it’s kind of disappointing to think that there’s no one [who can challenge Rousey]. We’re going to see her fight Miesha Tate, or that other girl. I can’t even pronounce that other girl’s name.”

Rousey is the woman who made women’s UFC possible, and now she may signal its downfall, as Kelefa Sanneh details in a New Yorker profile this week. To make it into the UFC, Rousey had to be the most captivating women’s MMA fighter the world had ever seen: An unapologetic trash-talker, a California beauty, and so far, totally unbeatable in the cage. Since 2011, Rousey has won all ten of her pro MMA fights, all decisively—she’s won eight by forcing her opponent to submit and two by knocking her out. None of her fights have been decided by a post-fight decision among judges. In theory, Rousey’s stardom can only boost the careers of other female fighters. When the UFC signed her in 2012, it began building a women’s bantamweight division to supply her with competitors. The company gave Rousey a coaching gig on the UFC reality show “The Ultimate Fighter,” along with a fleet of up-and-coming female fighters to shape up. Even a loss to Rousey raises her challenger’s media profile, and her success encourages more young women to view the sport as a serious option.

But a serious opponent has failed to materialize. Rousey may be “too good” for her own good, ESPN says. A Rousey loss would be the “best thing for women’s MMA,” fan site Cagepotato insists. In the media storylines that coalesce around her fights, Rousey has turned from a fan darling and into a villainous heel. She’s won so much, fans root for her to lose. Rousey has begun to sing her competitors’ praises in an attempt to convince spectators that when they tune in, they’ll be watching a serious fight. Undefeated male fighters, like boxer Floyd Mayweather, also inspire hate, but no one believes that Mayweather’s success threatens to undermine the future of boxing. (And compared to Mayweather, Rousey’s brashness is subdued: She does not praise Justin Bieber or feud with T.I.).

Part of the problem is that female fighters need more than just skill to get noticed. Before Rousey, White didn’t believe that a competitor like Rousey was possible. “I went to a fight up in Northern California about eight or nine years ago, and I saw this woman that looked like Chuck Liddell fight this girl who looked like she had about five Tae Bo classes,” White told Sanneh. The subtext is that female mixed martial artists require both fighting skills and feminine looks to make them marketable. Rousey herself has struggled to walk that thin line: She suffered from bulimia earlier in her career, and has grappled with how to promote herself on the cover of Maxim while being taken seriously as an athlete. (Sanneh reports that “she intentionally arrived sixteen pounds over her fighting weight” to the Maxim shoot “because, she says, she didn’t want to glamorize her body in an ‘unhealthy’ state.”) But she’s also critiqued other fighters for failing to measure up. She’s razzed fellow American fighter Miesha “Cupcake” Tate for being too girly (“I think she probably wears a push-up bra under her sports bra,” she said once), and has deemed Brazilian fighter Cris “Cyborg” Justino too manly. After Justino tested positive for an anabolic steroid in 2012, she “ceased to be a woman anymore,” Rousey told Sanneh. “In a perfect world, she would be a girl and not an it.”

One fighter who could conceivably follow in Rousey’s footsteps is 24-year-old American Kayla Harrison. At the 2012 Summer Olympics, she became America’s first-ever gold medalist in judo, and she’s considered taking her talents to the Octagon when her Olympic career is over. But her weight disqualifies her from taking on the 135-pound Rousey—Harrison says that her ideal fighting weight is 155 pounds—which right now seems a veritable requirement for making it as a woman in MMA. And there’s another reason why the UFC might deny opportunities to a heavier female fighter. “Fans don’t really wanna see us big girls out there,” Harrison said. “It doesn’t matter what I have to offer as an athlete, part of the gig is that I’m also pretty, and good in front of a camera, and marketable. It’s up to the MMA gods to decide that.”

Soon, Rousey’s stardom may vault her beyond the Octagon. She’s recently landed roles in the Entourage movie and The Expendables 3, following the trajectory of former MMA star Gina Carano, who gave up fighting (though she never made it to the UFC, she fought for smaller promoters like Strikeforce and World Extreme Fighting) to become a Hollywood action hero. And then what? Will women’s MMA get kicked out of the big leagues, left to await its next once-in-a-lifetime star? Even after finding a star in Rousey, the UFC faces a classic problem in women’s sports: The company may believe that women’s MMA is ultimately unsustainable because most competitors aren’t up to the challenge. But at a time when most women who enter the sport have few professional opportunities—until recently, only women in Rousey’s weight class could compete in the UFC (the company just staged its first fight-ever strawweight bout between 115-pound female fighters, which won’t do women like Harrison much good), and Rousey wins the bulk of the prizes and marketing money—there is little incentive for a large number of women to get into MMA and thus raise the level of competition.*​

Ronda Rousey is an extraordinary athlete. But if we want to see more women like her, companies like the UFC need to invest more seriously in women’s athletics—and not just throw all of their resources behind the one exception to the rule.

*Correction, July 21, 2014: This post originally stated that the UFC only hosts fights for women in Rousey’s weight class; the UFC recently added a strawweight division.