> Oh, well, Forex rates! Go try to buy USD with RUB for this rate. Go try to wire those USD out of Russia. Go try to withdraw your USD in cash. Go try to export that cash from Russia.
I am sorry for sounding like a jerk, but you don't understand the current situation in Russia.

I mean, you must live in the U.S., which explains why you think your experience generalizes to the whole world and why you think if something is unavailable in the U.S., then it must be unavailable in the whole world.

But for other readers, consider for a moment that there is a world outside of Europe and North America. Consider for another moment that the vast majority of the planet lives in that world -- the world where Russia isn't being sanctioned, where you can purchase Russian output and sell goods to Russia, and demand for Rubles is high because even in the poorest nation on earth, they still need to buy oil, wheat, and fertilizer. They may not be importing a lot of iPhones, but Russian output they will import. This is why despite the sanctions imposed by a small minority of nations, the majority of nations is still purchasing Russian output, which is why Russia exported more to the rest of the World in 2022 than what was purchased in total in 2021. Shocking, I know.

In terms of how you trade fiat currencies, you need to keep in mind that fiat is non-convertible and therefore doesn't leave its own banking system.

All dollars are held in the U.S. system, and for a foreigner in, say, Brazil, to buy dollars, they become a depositor of a bank in Brazil which has a relationship with a bank in the U.S. that is a correspondent bank for the Brazilian bank. The Brazilian bank is a depositor in that U.S. bank, and the U.S. bank buys the dollars and holds them in an account assigned to the Brazilian bank, but which actually exists in the US system. Then the Brazilian bank creates a matching entry in the Brazilian system and assigns ownership of that corresponding account to you. But the dollars stay in the U.S. (here I am ignoring paper money, which can travel, but isn't important for forex rates.). When you decide to sell the dollars, the clearance happens in the U.S., someone else -- either a foreigner with a correspondent bank or a local with a direct domestic bank -- has the money transferred from the correspondent account to their account.

So to buy pounds, you need an account with a bank that has a correspondent account in England, and has reserves in the Bank of England. The pounds never leave England. That is how you buy pounds.

To buy Rubles, you need an account with a bank that has a correspondent account in Russia, and stores reserves with the Russian central bank. The largest correspondent bank is Sberbank. I am sorry that your local bank doesn't have a correspondent relationship with a Moscow bank, but there are plenty of other banks that do outside of that walled garden. This is how Japan and China buy oil and gas from Russia, for example.

So that is how you -- or rather, someone who has escaped the walls of the garden -- can own foreign fiat currencies. In terms of how you trade them, well, dollars are traded in US exchanges, CNY is traded in Chinese exchanges (there is a parallel currency for Hong Kong traded in HK exchanges) and rubles are traded in Russian exchanges. I understand you think the US exchanges are the entire world of forex exchange - perhaps you think they are the entire world of investment -- and that only a black void exists outside of that, but really there are currency exchanges all over the world. The forex rate I cited was from Moex (which is the largest), the Moscow exchange. The volume of forex transactions in Moex is about 18 Trillion rubles a month. After the Western sanctions, there was a decline in volume of about 30% as the Western customers exited the exchange, severing their correspondent relationship, so it would be about 25 Trillion forex transactions per month before the sanctions. Nations outside the West -- primarily in Asia -- account for that remaining 70% of Moex flow, 18 Trillion rubles a month is plenty of flow to support a net trade surplus of 330 Billion a year.