That's a nonsensical statement. Use BTC to buy a car today, and then use it to buy the same value car in a year. BTC is, fundamentally, unstable at this point in time. Even when all BTC is mined and it is distributed across the globe to every human being and sentient AI and animal, it will likely continue to be highly unstable as a currency.
Compare to the, relatively, stable USD as a currency. Prices for goods and services in USD fluctuate, but typically only changing once a year or so. Your milk price doesn't, in USD, shoot up by 500% in a week.
It's all a matter of perspective. It's the entire rest of the world that's unstable and undergoing wild price fluctuations, while the value of one Bitcoin stands eternal and unchanging by virtue of it being worth one Bitcoin. /s
And many things are cheaper. Or they aren’t growing with inflation anymore. Most electronics, for instance, and many mechanical devices. Even food stuffs (some) have been more stable in price than inflation suggests they should be.
