SAN FRANCISCO — No one wanted to miss out on the cryptocurrency mania.Over the last two years, as the prices of Bitcoin and other virtual currencies surged, crypto start-ups proliferated. Companies that market digital coins to investors flooded the airwaves with TV commercials, newfangled lending operations offered sky-high interest rates on crypto deposits and exchanges like Coinbase that allow investors to trade digital assets went on hiring sprees.A global industry worth hundreds of billions of dollars rose up practically overnight. Now it is crashing down.After weeks of plummeting cryptocurrency prices, Coinbase said on Tuesday that it was cutting 18 percent of its employees, after layoffs at other crypto companies like Gemini, BlockFi and Crypto.com. High-profile start-ups like Terraform Labs have imploded, wiping away years of investments. On Sunday, an experimental crypto bank, Celsius, abruptly halted withdrawals.The pullback in the crypto ecosystem illustrates the precariousness of the structure built around these risky and unregulated digital assets. The total value of t …
