In a deflationary system, rich people just hold money, and earn more in interest from holding the money, than everyone else earns combined. They use that interest to buy things from the poor while not producing or investing themselves. Poor people realize if they switch currencies they can have more things because they don't have to give a percentage of everything to the rich. This makes the system unstable.
Bitcoin might be approaching it.
Spending shouldn't be the goal, but exchange of goods and services should be. Representation of real value should be a goal. If you can receive real goods and services as a consequence of holding numbers on a spreadsheet, instead of a consequence of providing real goods and services yourself, the economy has a problem. Maybe a system with zero inflation or very slight deflation can be stable, but the extreme deflation seen in Bitcoin is destabilising.
Bitcoin might be approaching it.
Spending shouldn't be the goal, but exchange of goods and services should be. Representation of real value should be a goal. If you can receive real goods and services as a consequence of holding numbers on a spreadsheet, instead of a consequence of providing real goods and services yourself, the economy has a problem. Maybe a system with zero inflation or very slight deflation can be stable, but the extreme deflation seen in Bitcoin is destabilising.