I'm not sure quite what they meant, but that doesn't sound quite right to me either.
If the currency is stagnant or close to stagnant, the incentive to invest is that you end up with more wealth overall.
I'm not sure it's possible for deflation to be both predictable and higher than the market rate of return, because people today would immediately speculate and bid up the price of the currency to reflect its future expected value.
Of course inflation is an added incentive to invest money, or at least to store your wealth in assets other than money.
If the currency is stagnant or close to stagnant, the incentive to invest is that you end up with more wealth overall.
I'm not sure it's possible for deflation to be both predictable and higher than the market rate of return, because people today would immediately speculate and bid up the price of the currency to reflect its future expected value.
Of course inflation is an added incentive to invest money, or at least to store your wealth in assets other than money.