Thinking about this more, I have come to realise that not all money is equal even in the fiat realm. Most people look at fiat as they look at Bitcoin: along the single dimension of market price in the local currency.

$1 = $1 and 1BTC = 1BTC, right?

However there are intangible values to cash which I would estimate AT LEAST in the range of 2 - 3% for the privacy, finality, and portability you get. It sounds ridiculous but $100 in cash is indeed worth $102+.

For example: If there is a power cut or network issue that means your debit card won't work when you need it most (buying food, gas in a storm), what premium would you pay to still be able to transact? That is the value of cash.

How about having your bank account frozen for some political reason, what premium would you pay to have the cash on hand to still pay your rent and not get kicked out? That is the value of cash.

How about wanting to buy with absolute privacy and finality? That is the value of cash.

This intangible value of cash is on a different axis and so is hard for most people to understand at first until you need it the most.

Ultimately, if you are on a Bitcoin standard, the interface between you and the vendor does not actually matter too much right now (Besides tax implications). Lightning, stable coin, and cash all fill the roll of an interface for value transfer. With cash I am "pegging out" into fiat to make the payment and not holding it so there is no value lost to inflation. The main thing is that your savings are not being held in fiat so they are not being debased.