It's enough to make Amazon's Jeff Bezos gush with envy: young Chinese shoppers spent at least $5.7 billion in a single day on Monday.

China has roughly 591 million Internet users -- equal to the combined populations of the U.S., Brazil and Thailand. On Monday alone, more than 400 million unique visitors shopped on online shopping portal Alibaba. Perhaps the Obamacare folks can learn something about bandwidth capacity from China; a population the size of the Euro zone shopped without incident on a single company's website.

Of course, China boasts another 1 billion-plus people who have yet to become active online buyers. Needless to say, the growth potential of Chinese e-commerce is titanically large, unlike anything seen before in history. That's great news for Alibaba, the Amazon of China, and its ilk.

Yet at least one element of Monday's record-breaking shopping extravaganza should worry the Communist Party: the fast-rising number of single men who are now celebrating "11/11," the occasion for the online splurge. The "Singles' Day" holiday is a Chinese twist on Valentine's Day, an occasion for the lovelorn to console themselves with a bit of retail therapy. Chinese love numerology and, as we all know from Three Dog Night's pop classic, one is the loneliest number. The date 11/11 is made up of four of those lonely numbers. Some also refer to Nov. 11 as "Bare Branch Day," the day of being unwed.

This gets at an underappreciated crack in the veneer of Chinese stability: too few women.

China's demographic challenges are well known. It's become a cliché, for example, to say China will grow old before it gets rich. Less talked about is China's dangerous, and growing, gender imbalance. This testosterone glut is perhaps the most unintended side effect of the one-child policy. Economics explains China’s cultural preference for sons. When they get into their elderly years, parents can hope to live with their son. A daughter might enter into another family system upon marriage, leaving parents without a safety net.

Estimates for how may more men China will have reaching adulthood than women by 2020 range between 30 million and 40 million. Demographer Nicholas Eberstadt of the American Enterprise Institute in Washington has taken an even longer-term look at the world's most competitive dating market. By 2030, Eberstadt predicts, more than 25 percent of Chinese men in their late 30s will never have married.

Not surprisingly, this "marriage squeeze," as Eberstadt calls it, will be most pervasive in the countryside, among the poorer and less-educated of China's 1.3 billion people. Trouble is, this is exactly the demographic that worries Communist Party leaders in Beijing when they mull the risks of social instability. This simmering problem will become acute on Xi Jinping's watch as he and Premier Li Keqiang pledge to tolerate lower gross domestic product growth in their effort to restructure the economy. How will Beijing cope with tens of millions of underprivileged, unmarried and, well, frustrated young men?

Demographer Valerie Hudson has explored this risk extensively, titling a 2004 book she wrote with Andrea M. den Boer "Bare Branches: The Security Implications of Asia's Surplus Male Population," and a more recent one “Sex and World Peace.” Hudson says that among the steps China should consider to avoid the kind of dystopian future mulled by science fiction writers is moving to a two-child policy.

Beijing will surely say butt out, this is a purely internal matter. Not so. Officials in Myanmar, Mongolia and Vietnam already are decrying the increasing flow of marriage-age women to China. Martin Walker of the New School University of New York, warns of "The Geopolitics of Sexual Frustration." Harvard’s Niall Ferguson questions whether too many bachelors could catalyze Arab Spring-like uprisings in Asia.

Environmentalists will clearly shudder at the idea of Chinese families suddenly having two or three kids. There's already grave concern about our planet's ability to sustain 7 billion humans, never mind 8 billion or 9 billion in short order. Fair enough. But there can be little doubt that Xi and Li must find ways to achieve better gender balance.

Building a more extensive safety net might make couples less linearly focused on having a son. That includes helping families bear the fast-rising costs of health care and education. Officials might also consider tax incentives to welcome daughters into the world. And who knows, a national program to educate parents on the importance of gender balance might even help.

Xi and Li had better start worrying about how frustrations over a system rigged in favor of party elites could fuse with the unmet sexual needs of tens of millions of very lonely men. Go ahead and revel in setting a one-day shopping record. Just be wary about the demographic trends that have made "Singles' Day" such a huge phenomenon.

(William Pesek is a Bloomberg View columnist. Follow him on Twitter.)