> "Given the fact that you are losing value on savings due to the central bank increasing the supply of money, you also have to take into the account the amount of time it took you to save up the 100K."
Presumably the hypothetical subject isn't saving money by stuffing it in a mattress. In which case the interest rate on their savings should have been at least able to track inflation.
Right now in the US, interest rates on savings isn't keeping up with inflation. Not sure what macro-econ says about the sustainability of such a situation, but current fed policy is definitely penalizing savers in the short term.
And the current economic situation is an aberrant special case; it isn't implicit or ever-present.
And, even still: I think anyone whose annualized rate of return on savings -- over the last, say, ten years -- has fallen below the rate of inflation, can be safely said to have invested in a manner tantamount to stuffing it in a mattress.
Presumably the hypothetical subject isn't saving money by stuffing it in a mattress. In which case the interest rate on their savings should have been at least able to track inflation.