Uber’s public downfall began in February, when Susan Fowler, a former engineer at the company, wrote about enduring sexual harassment and discrimination there. Other employees came forward with stories. One involved a manager groping employees’ breasts. Mr. Kalanick’s own bro-hood became part of the story when a video surfaced showing him berating a Uber driver who complained that Uber’s price cuts had driven him into bankruptcy. Mr. Kalanick said the driver needed to take responsibility for his own life.

As this was happening, Google’s self-driving car unit sued Uber, alleging it had stolen its ideas. Then word leaked that Uber had been using a sneaky software tool to deceive regulators in cities around the world. All this is as much a part of “bro culture” as the poor treatment of women; the point is to get away with as much as you can.

Hoping to right the ship, Uber appointed one of its board members, Arianna Huffington, to join former attorney general Eric Holder and others to investigate the sexual harassment claims. Mr. Kalanick has apologized and vowed to “grow up.” (He’s 40.) Most important, Uber has announced that it is planning to hire a chief operating officer, ideally a steady hand like Sheryl Sandberg, the chief operating officer of Facebook. It’s a great idea, but it should have happened years ago. Now it may be too late.

Ms. Huffington insists the board has full confidence in Mr. Kalanick. But should it? He’s a college dropout with a spotty track record and a reputation for pugnacity. His record at Uber includes racking up enormous losses — reportedly $5 billion over the last two years. Despite this, the bluest blue-chip investors (including Goldman Sachs and Morgan Stanley) have invested a total of $16 billion in Uber.

Bro C.E.O.s are better at raising money than making money. So why do venture capitalists keep investing in them? It may be because many of the venture capitalists are bros as well.

Venture capitalists used to be tech engineers who had made a bundle, retired early and took up investing in start-ups as a kind of white-shoe hobby. The new breed are competitive alpha males who previously might have gone to work as bond traders. At the same time, there are fewer women. In 1999, 10 percent of investing partners at venture capital companies were women. By 2014 the number had declined to 6 percent, according to the Diana Project at Babson College. This is probably one reason that, despite many studies showing that women run companies better than men, none of the 15 biggest tech “unicorns” — start-ups worth more than $1 billion — has a female chief executive.

Uber’s collapse should not come as a surprise but it does offer a lesson: Toxic workplace culture and rotten financial performance go hand-in-hand. It’s possible for a boorish jerk to run a successful company, but jerks do best when surrounded by non-jerks, and bros do best when they hire seasoned executives to help them. Without “adult supervision” and institutional restraints, the C.E.-Bro’s vices end up infecting the culture of the workplaces they control.

This poisonous state of affairs will get fixed only when investors start getting hurt. A crash at Uber, the most high profile tech start-up in the world, could provide the jolt that finally brings the tech industry back to its senses.