How has the average life experience between the quintiles changed? I think this is something that cannot be so easily quantified, even more so when there's subjectivity involved in the quantification. So for instance it's easy to consider ourselves rich when we do things like look at prices 'back in the day.' A quick search for prices in the 50s gives me $21 [2] for a toaster in 1951. That'd be about $200 today. So, at a glance, it makes it seem like we must be fabulously wealthy for anybody to be able to afford for $10 or $20 what would have been a fairly meaningful purchase back then. But then we get into weird things when we start looking at relative pricing. Another datum [3] there is that you could get a 1958 Chevrolet Corvette for $3631 in 1958 dollars. But wait... that's only about 180 toasters...? In toaster relative prices that'd be like getting a nice Porsche today for $1800 - $3600!
Of course the relative prices of things change over time, and this is something that inflation completely misses. I'd be curious to know exactly how, which is why I think examining a representative lifestyle in the different quintiles over time would be most informative. How much of the representative income was spent on what things? How distant were their remaining consumer desires away from their means? How much were they able to save? What would be the expected economic impact of some sort of emergency? Inflation alone is far too imprecise a measurement to answer these questions or, equivalently, to justify the grand statements it's used to make.
[1] - https://www.fool.com/investing/2016/09/25/how-much-does-the-...
