Okay I had a long talk with your brother about this, let me see if I can summarize it for you.
Right now, oil is not bought using exclusively US dollars. I do not need to buy US dollars in order to purchase oil Oil is priced in US dollars. It is completely arbitrary. It would not matter if it were priced in Rubles, Yen, Pounds, or Crazy-Fun-Time dollars… it is just the arbitrary unit we have placed behind it. Think of it like this… will it change the temperature outside if you measure it in Celsius instead of Fahrenheit or kelvin?
Lets say I live in Japan. I have 100 yen and I want to buy oil from someone in India. We’ll say that 50 yen is = 1 US dollar (which is what Oil is priced in). And we’ll say that 10 Rubles (Indian money) is = 1 US dollar. I go to my vendor in India and say “Hey I have 100 yen and would like to purchase that much oil from you.” He looks at the exchange rate and sees that my yen is worth $2 (100/50 =2), and that $2 would be worth 20 Rubles… and then he gives me however much oil 20 Rubles will buy.
Let me be clear about this…. no one is buying physical US dollars to purchase oil with anymore. Back in the early 80’s before computers took over, sure that is how it was done. But not today. In fact there isn’t even enough physical paper money out there to account for half of the money “in circulation.” These days you have imaginary numbers on a computer screen. I want to buy something, my imaginary number changes to zero, the person I’m buying from sees their imaginary number go up, and then they send me the product.
Even if that were the case… The US had the most powerful economy on the planet (with low levels of inflation) for 30–40 years before the petrodollar became a “thing.” If you broke up our entire economy right now by the states but still counted us combined as an economy, California alone would be the #3 economy on the planet. There is no concern. It is conspiracy theorists who don’t understand economics.