> you have vivid memories of how quickly the AUD, or USD or any fiat currency really has been so immensely rapidly inflated in the last 20 years; hell just in the last 3 years

I actually think the last 20 years have had remarkably little inflation in the grand scheme of things, compared to the last 100 years, at least in the UK.

I first got interested in this just under 20 years ago when my mum said that my grandma's first house cost exactly £100, and at the time the property market was towards the end of a massive boom (and then was stagnant for about the next 10 years). At the time, her £100 house would have been worth somewhere around £100k, which got me thinking to how crazy that it could have increased a thousand fold. Looking at UK historical inflation rates, it was interesting that from 1900 until the mid 1980s, inflation was pretty constant at around 7% per year, which has the interesting side effect that when compounded, prices approximately double every decade.

Obviously, my data points are skewed towards the UK, but I suspect the US and Europe at least experienced similar effects, because of the ease of international trade, so any imbalances would be rapidly exploited by the market until they equalised. However, one data point I have from the US, which is a bit fuzzy in my recollection so it might be slightly off, was from reading Grapes of Wrath set in the 1930s Great Depression. IIRC the daily salary for a long day picking cotton was around 20 cents, so maybe the specific inflection points in the US timeline were different, but it seems to have followed a similar long-term inflation pattern when considered over several decades.

Things got weird in the UK, as the mid-late 80s had some unprecedented high inflation rates (I remember my parents paying 12% interest on our house at the time), followed by very low inflation for about a decade (the UK government was targetting 2%), which led to a lot of surplus money around, easy borrowing for industry, and ultimately a massive rise in house prices in the early 2000s (and I was interested then because I was trying to buy my first home, and for example where I was looking house prices rose 50% in 2003 alone). Since then, we've had unprecedentedly low interest rates (nearly zero) leading to quite low inflation for a couple of decades.

What's interesting now though is that people are seeing "high" interest rates of 5% and panicking because younger buyers now have only ever experienced relatively low interest and inflation rates, but actually if you consider a longer time frame, the last 20 years with its sudden inflation spurt then prolonged price stagnation and now "high" inflation again, it's probably on average bringing us back to that average of 7% that we saw over a longer period.

Another thing that's really interesting is when and why inflation started happening, sometime around the 15th and 16th centuries, when people started speculatively investing in companies. Prior to that, prices of commodities and housing had been rather static for quite a few centuries.

There are lots of fascinating articles online about medieval prices, e.g. https://blog.datawrapper.de/medieval-prices-wages/