Plans for Facebook's proposed "stablecoin," Libra, appear to be unraveling with the withdrawal of PayPal, Visa, Mastercard, Stripe, eBay and Mercado Pago as potential sponsors.

This is hardly surprising, given growing awareness of Libra's potential adverse consequences. If it offers anonymity to its users, Libra will become a platform for tax evasion, money laundering and terrorist finance. If, on the other hand, its privacy protections are lax, Libra will give Facebook access to users' most intimate financial details.

Then there are the dangers Libra poses to economic and financial stability. Although Facebook's stablecoin will be backed by a portfolio of "low-volatility assets," anyone who lived through the 2008 global financial crisis will know that low volatility is more a state of mind than an intrinsic attribute of an asset.