Well no one should ever hold $1 million in cash, invest that shit. That has literally nothing to do with how useful fiat currency is. In fact you'll probably need to convert that bitcoin to "fiat" to buy more real estate!
Yes, I know recently a house was bought using crypto but that's hardly the norm and it won't be for a long time.

In fact, real money isn't going away until corporations start paying people in something else.

Also, controlled inflation is a good thing for a currency. Bitcoin's deflationary nature makes it a better investment, but a worse currency.