The money supply has increased pretty reliably at about 7% per annum for like 50 years. Mostly mild fluctuations with a few exceptions. I would pose the question as to why you can get a 4-5% mortgage right now?
I think the answer is that we have to have a clear way to measure against the past. It’s only in the comparison to a harder asset that has enough liquidity that we can even see the degradation of the currency and accurately price it. (CPI is total garbage for this)
This is why I think the presence of bitcoin is the only thing that will actually restore real interest rates.