that is a terrible idea. Even ignoring the energy use and that market cap is a bad metric for value, especially in a market with as much wash trading and painting the tape and just plain fraud as the bitcoin ecosystem.

The code base is under the control of around 5-10 people, the mining is under the control of 2-5 mining pools, with the largest two being the result of the largest pool splitting because it was too big and that's not good optics, the majority of those pols and mining is in China. It has not reliably relayed transactions, being severely congested for weeks on end several times in its history. It does not have a "stable fiscal policy", it has no fiscal policy. It is limited to 7-10 transactions/second (and no, lightning does not solve this, as you still need a regular transaction to settle, onboarding something the size of the EU would take on the order of 50 years until everyone has their channel, and then another 50 years if everyone were to settle their channels, along with many others fundamental problems with lightning), completely laughable if you want to use it as the backbone of the international financial system.

You want there to be a proper fiscal policy with knobs that can be turned, so you can deal with crisis/extraordinary events. For instance having your country's currency tied to the dollar is horrible for managing that country's economics and only done if there is no other alternative, using bitcoin as the global reserve would be that, just on crack and there's no reason to do it unless you're incredibly desperate, in which case the dollar is still a safer bet. You'd hand over control of your financial system to a shadow group of unelected people, so you lose even more autonomy. You want there to be checks and things like sanctions, to prevent fraud, theft and, in the case of sanctions, to have a political tool that is harsh but less so than an actual war. These things are features, not bugs. You can debate whether it's good that the US is in control of a lot of these tools, but proposing to get rid of these tools altogether (which moving to bitcoin would do) would be even worse. There is no country that has gotten itself out of debt using bitcoin, so saying it is a solution is disingenuous at best.

These are just the same old bitcoin talking points that make it sound like it could actually work but do not hold up to the tiniest amount of scrutiny. And the end goal is always to just make the price go up so the gambling pays off, not any use case or making the world better or anything.