Financial losses for today’s start-ups are much more common than they were decades ago, and the losses are much bigger. VCs are making back less from their initial investments than at any point since the global financial crisis of 2007–9. According to a study by Jay Ritter, only 22 percent of start-ups were profitable in 2021, the year of peak IPOs, versus 80 percent in the early 1980s. And today’s start-ups are not...