Arguably, modern currencies are backed by the ability of nation states to demand tax payments in them, creating a steady and stable (due to being directly proportional to economic activity) demand for them.

A currency having value abroad is arguably a side effect, not the main goal.

Of course, it is everyone's taste. One values USD more and other BTC more. Objectively, so far, BTC was a better investment. And given some 80% of BTC was already mined and there will be no more BTC ever while 20% of USD was printed this year (edit: sorry, in 2020), I undestand why some people stash Bitcoin. I have maybe 0.5% of my net worth in it, but I am very happy for those 0.5%.

>Objectively, so far, BTC was a better investment.

Dollars are not meant to be an "investment". The fact that the supply can be increased on demand is a feature, not a bug.

The economical and political power of the US is the reason for that. And the military might is what backs up the political power.

The same pattern repeats itself in history: those with the biggest army popularize their culture, language and coin. The Roman Empire is a good example.

See https://en.wikipedia.org/wiki/Hegemony

So how do we explain international use of the Euro and Swiss franc?