1) convenient defaults. People trade in dollars for the same reason they speak English - because it's mutually convenient between two different countries with their own language and currency. This is partly due to sheer size and partly due to successful cultural export.
2) clearing and settlment. This is not well developed globally, so in practice a lot of smaller countries, foreign banks, and multinationals keep US bank accounts so they can more easily handle payments. This system plays by US rules, which is why the EU is constructing a parallel one to trade with Iran.
3) "eurodollars". I don't fully understand this aspect but apparently this market is coming under regulatory pressure.
One of the more comical illustrations of this is that the US passed a law during the Bush administraron authorizing invasion of the Hague if US officials were to be tried in the ICC. Less amusing is story after story of US-authorized violence to depose governments perceived as hostile to US business interests and slaughter supporters of the deposed governments.
You might find this comical, but many dutchmen find it absolutely abhorrent that the US is willing to enact suchs an aggresive policy into law, especially as the dutch have been close allies with the US for a very long time.
authorizing invasion of the Hague if US officials were to be tried in the ICC
The benefit comes mainly from lower borrowing costs. The harm comes from the higher exchange rate that hurts competitiveness of US exports.
https://www.mckinsey.com/featured-insights/employment-and-gr...
>In a “normal” year for the world economy, we estimate that the net financial benefit to the United States is between about $40 billion and $70 billion
As one specific example, the low rate of saving by US consumers is a direct consequence of the use of the dollar as a reserve currency. It's not clear to me that lower borrowing costs, even if those are present, outweigh even that one harm.
And to be clear, "the United States" as a whole that's benefitting in the mckinsey report you link is an average. The actual benefits and harms from the use of dollars as a reserve currency flow to different people, and as far as I can tell that contributes to worsening inequality in the US, which is an effect (benefit or harm, take your pick) the mckinsey report doesn't seem to mention.
US has floating exchange rate and it adjusts automatically the international balances. Because US has no debt denominated in foreign currency, it is shielded from hyperinflation and other issues that Venezuela and other countries suffer.
But Russians get paid in local currency. If that crashes in relation to the usd, go ahead, make the $280 mortgage payment. It will be xx% more expensive this month while your salary and expenses stayed the same.
This administration is bringing a serious rift in transatlantic relations, and that is a bad thing for both sides.
Maybe you'll find a 2-3 obscure banks giving mortgage loans in USD in Russia. Although I'm not sure about even that.
And in the last 10 years you won't find a sane person that will apply for loan in USD in Russia.
I'm always surprised when people from the West discuss the economical/political issues in Russia while they know absolutely nothing but the typical media propaganda. Typically: "The only truth about Russia can be found in our media, not even the Russians themselves know anything about politics, economics, banks, loans, etc in their own country".