> Fiat currency: Why would I hold a currency that another nation sucks the value out of by printing it? Even the dollar has half its value stolen every decade.

Because the entire point of a reserve currency is to spend it in emergencies. Store of value is second to liquidity.

You can also usually recover some of that loss depending on how you are holding it.

> Gold stock above ground doubles every 40ish years, halving it's value each time. Think how difficult it is to safely move and assay billions of dollars worth.

Sure, that's a potential issue (although you are overstating it a bit). The main point is that due to historical reasons it is generally really easy to sell gold even if the world is falling apart their will always be a buyer.

> The reason nations aren't publicly using bitcoin as a reserve is that it's still only the year 2025

Sure, and part of the reason is that bitcoin doesn't have a track record of providing the properties countries need in a reserve currency. Reserve currencies aren't the place to try radical experiments. A lack of track record makes bitcoin a poor choice in and of itself.