SAN FRANCISCO — Fred Wilson, a venture capitalist at Union Square Ventures, recently published a blog post titled “The Great Public Market Reckoning.” In it, he argued that the narrative that had driven start-up hype and valuations for the last decade was now falling apart.

His post quickly ricocheted across Silicon Valley. Other venture capitalists, including Bill Gurley of Benchmark and Brad Feld of Foundry Group, soon weighed in with their own warnings about fiscal responsibility.

At some start-ups, entrepreneurs began behaving more cautiously. Travis VanderZanden, chief executive of the scooter start-up Bird, declared at a tech conference in San Francisco last week that his company was now focused on profit and not growth. “The challenge is to try to stay disciplined,” he said.