Stock analyst Lyn Alden argues it is not.
The broadest definition of a Ponzi scheme refers to any system that must continually keep operating to remain functional, or that has frictional costs. Bitcoin doesn’t really meet this broader definition of a Ponzi scheme any more than the gold market, the global fiat banking system, or less liquid markets like fine art, fine wine, collectable cars, or beachfront property. In other words, if your definition of something is so broad that it includes every non-cashflow store of value, you need a better definition.
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