But you just said there would be inflation and the inflation would be higher than the interest.  I would simply keep my real Bitcoins and while the nominal number won't change the purchasing power of it will.   Your system assumes everyone is stupid and opt for inflationary non-Bitcoin tokens instead of the "real thing".  Even if people temporarily did that, the scenario requires them to be stupid over an extended period of time. They would need to see that year in and year out they have a decline in real purchasing power and continue to not act by taking the very easy step of taking their coins out of the bank.