The dollar doesn't change value like Bitcoin, not cash as a whole.

What we define as a good currency doesn’t. A currency that inflates or deflates dramatically is foundering.

So are we talking about "a good currency", or "cash"? Because the initial comment said "cash".

I guess we’re just establishing that Bitcoin doesn’t fit the definition of a functional currency of which cash is a subset.

I disagree, I think Bitcoin is excellent digital cash, but not of a great currency yet.

oh yes it does, it has crashed more than 2000% vs Bitcoin in a decade.

That’s completely wrong. You would never say “the US dollar has crashed compared to Microsoft stock“. That’s a dumb comparison to compare a currency to an investment. The dollar has been mostly stable the past 10 years. A gallon of milk is still around $3.50

why are you comparing a currency (bitcoin) to a stock.

USD vs Bitcoin is a comparison of currency.

Bitcoin is a security closer to gold than anything. Limited supply and high cost of production.

The dollar also lost a lot of value when compared to the stock market, or compared to land prices, or to gold.

The value of cash dollars changes all the time. You just don't notice it because you pay for everything in the same dollar denomination. But when everything gets more expensive year by year that's your dollar devaluing. CPI is one measure of that.