You need somebody who wants riyal for dollars. Why would the chicken seller not take the riyal since that helps his customers and do the FX magic themselves? "Local currency sales" is what marketing men recommend. It's just the latest form of vendor financing.
Who wants riyal for dollars. People who buy kebabs in Saudi. Those who live and work there.
As I said the dollars are useless in Saudi, because that's not the local currency stuff you need day to day is priced in.
The point again is that in aggregate you can buy things in the currency you have and you can sell things for the currency you want. The financial system smooths the path to that deal - for a price.
As anybody with a Paypal account and who trades internationally understands.
They buy the dollars they need to buy the chicken off the Saudi national bank for Riyal. That’s their job. Controlling that rate is a primary way the SA government manages their domestic economy.
This is simply outright wrong.
According to Wikipedia, the last arms deal that Saudi Arabia struck with the US was, that alone, around $350 billion.
That's more than most of the nation's GDPs.
Trying to put a Ponzi scheme such as Bitcoin on par with the US dollar is either an entirely clueless assertion or a disingenuous claim made in line with all the other pump-and-dump schemes that plague the so called crypto currencies.
Vendors/citizens of some other countries - Jamaica, many parts of Mexico, many parts of Canada, also are happy to deal in USD as a customary business practice, at least in my experience.
So outside of the US, no USD is not just a store of savings, it's a means of repaying debt. Hence why people want it and will accept it as a first preference over most other currencies when international transactions need to be made.
Your personal balance sheet moves in the same direction from a lower value to a higher one.