So Anthony Weiner becomes the latest politico to jeopardize his career by making a fool of himself on the sexual front. A man with an informed, detailed familiarity with issues surrounding health care reform, who so humanely advocated for medical aid for the 9/11 responders, gives in, like a kid in junior high school, to the impulse to Twitter a semi-obscene underwear shot and put other unclever risqu? photos on the Web.

A lot has been written about why prominent and/or powerful people act out sexually. Enough, in fact—and much of it quite convincing—that that issue can be left to the experts. But when people like Weiner risk their effectiveness—for what? Not even for love, like England’s Edward VIII, but for a whim he’d regret later even if professional tattler Andrew Breitbart hadn’t brayed about it to all the world—it’s not only Weiner who’s the loser.

The American economy is in the worst shape many people born after the Depression can remember. The educational and financial prospects for young people are dismal. People are dying for lack of health care. The fabric of climate is fraying because of global warming; as Arizona burned last week, people in tornado-ravaged Springfield were collecting their bedroom furniture from their neighbors’ yards. You’d think all that would be enough to make people who understand the dangers we face, and have the power to do something about them, take what they’re doing seriously enough to control their behavior so idiotic pranks won’t undermine what influence they have.

When Dominque Strauss-Kahn, former head of the International Monetary Fund, was arrested following allegations that he sexually assaulted a hotel maid, philosopher Bernard-Henri Levy lamented that the court “pretended to take him for a subject of justice like any other” though socialist Strauss-Kahn had been a defender of “the most fragile and vulnerable” nations. What’s lamentable isn’t that Strauss-Kahn was treated like any other accused criminal. It’s that he didn’t care enough about those fragile and vulnerable countries to manage his personal life in a way that would ensure his continuing role as their advocate.

The same goes for Weiner and others—for Eliot Spitzer, for example, who as New York State attorney general went after predatory lenders, crooked investment managers, firms fixing computer chip prices and other white-collar offenders. While that may explain why his partying with prostitutes was brought to light, Spitzer must have known that his adversaries would be gunning for him.

Former U.S. senator John Edwards is another case in point. Edwards, an outspoken believer in global warming and a distinguished advocate of universal health care, is finished in politics. He’s facing federal felony charges after channeling nearly $1 million to cover up an affair that produced a child even as his wife Elizabeth, ill with the breast cancer that later caused her death, was supporting his campaign for the 2008 Democratic presidential nomination.

A few years ago an internationally known economist remarked privately that the people of France had no objection to their recently elected president’s marrying glamorous Carla Bruni, but they would have preferred for him to fall in love with them. Good point: real opportunity, the opportunity to affect the lives of millions of people, is rare. When people who have it don’t take it seriously, those millions lose their advocates. One reason we’re not gaining the ground we hope for on the economy, health care and climate change is that those who understand those problems and their remedies let themselves be distracted by the various excitements of public life instead of being passionate about their opportunities and their constituents.