By Dan Weil The digital currency market has faltered amid the meltdown of the FTX exchange with other companies suffering too. You can’t accuse economist Nouriel Roubini of pulling his punches on the subject of cryptocurrencies. The man given the moniker “Dr. Doom” for correctly predicting the financial crisis of 2008 has come up with seven “C” words to describe cryptocurrencies “Concealed, Corrupt, Criminals, Crooks, Con Men, Carnival-barkers, Cult, Crappy,” he wrote on Twitter. Roubini also included “@cz_binance” in that group, referring to Changpeng Zhao, chief executive of Binance, the wor…