Tony Yoo, a financial analyst, at home in Playa Vista, Calif., Aug. 17, 2018. Yoo invested more than $100,000 of his savings last fall. At their lowest point, his holdings dropped almost 70 percent in value. Despite his investment losses, Yoo said he was still a big believer in the idea that cryptocurrencies can provide a new way to transact online, without big corporate middlemen. (Rozette Rago/The New York Times)
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