This doesn't seem like a particularly big deal, until you realize what it does. Imagine the US pumps a bunch of funny money (I'm using a sardonic term just to clearly distinguish between organic/'real' growth) into our economy. This would naturally cause inflation. But here's where the fun kicks in. Oil is still by far the most in demand resource in the world. And now when countries go to buy oil they need to accumulate USD. But now due to inflation a country that wants to buy the same amount of oil needs to keep an even larger reserve of USD on hand. And that's exactly what happens. The USD becomes worth less and countries are obligated to hoover up more USD to ensure access to oil. As that USD starts getting removed from circulation, the effects of the inflation start to abate. Like magic, we can 'print' (not how many is made, but that's another topic) a practically unlimited amount of funny money with minimal economic consequences.
This also explains much of otherwise inexplicable actions in the Mideast and related places. We don't want their oil, we want them to sell their oil in USD only. This [1] is an article from Time in 2000: "Europe's dream of promoting the euro as a competitor to the U.S. dollar may get a boost from SADDAM HUSSEIN. Iraq says that from now on, it wants payments for its oil in euros, despite the fact that the battered European currency unit, which used to be worth quite a bit more than $1, has dropped to about 82[cents]. Iraq says it will no longer accept dollars for oil because it does not want to deal "in the currency of the enemy."" By 2003 we had destroyed the Iraq government and killed Saddam in a kangaroo court. Similarly with Libya, Gaddafi was aiming to create a gold backed 'Afro-currency' which is what he wanted to start selling his oil in. Two other nations which have moved against the petrodollar are Iran and Venezuela.
On the other side of things, this also explains Saudi Arabia. One of the most backwards and repressive nations in existence today, we're still BFF since they act like a loyal lapdog when it comes to the petrodollar. In exchange we let them do just about anything. The CIA has recently stated that Khashoggi's murder was likely ordered all the way from the top. I can tell you how this story will end. Do you remember in 2015 when Saudi Prince Majed Abdulaziz Al Saud had a rape and assault filled 'party' at a rented mansion in Beverley Hills? The 'party' was only stopped once a neighbor called the police after seeing a bleeding woman screaming for help as she tried to scale the fence of his mansion to get away. He was arrested and that's where most media reporting ended. The epilogue is that he was rapidly granted bail, got on a plane and simply flew back to Saudi Arabia with no consequences whatsoever.
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This is already getting long enough, but something very important now a days is that the petrodollar is dying. It's a mixture of a perfect storm of a large number different of factors, but it's definitely a dead system walking. And this has major implications for the future of the US economy. To date we've had 'economy armor' on. In the not so distant future, that armor is coming off and our economy will stand or fall under its own weight. And this is when being massively in debt suddenly does start to matter because if you just try to print your way out of it, you would not be able to rely on the petrodollar to protect the economy anymore.
[1] - https://content.time.com/time/magazine/article/0,9171,998512...
[2] - https://www.cbsnews.com/news/saudi-prince-majed-abdulaziz-al...