That sounds awfully counter-intuitive. Before there'd be nothing left to buy, the prices of things to buy would go up (i.e. inflation), which would discourage further hoarding.
Some early adopters would be filthy rich. Not so different from other filthy rich people. Hoarding would be more profitable than investing. Would everyone stop investing, would the currency just keep on deflating? Forever?
When a really rich person doesn't have to do anything at all to keep getting richer, what will he do? If he hoards until he dies, how will that affect the economy?