If you’re really going to follow the money, you ought to consider the international reserve status of the US$, the quality of the US$ as a store of value, and the current US$ holdings of KSA and other OPEC nations. Fact is that the US government is utterly dependent upon OPEC and China to finance its deficits, but the quality of the US$ has significantly deteriorated. Consider what would happen if KSA persuaded OPEC to price crude oil in gold instead of US$. This prospect makes our friends, the Saudis, very persuasive in such matters. And, like everything, the current crop of politicians will even make the US military available for a price.
Follow the possibility of a collapsed US economy followed by a collapsed US Government. The most powerful military in the world would then be temporarily leaderless. The closest parallel to this would be a "monkey with a hand grenade" loose in the world. If you don't think that possibility doesn't scare the crap out of the Saudis, you're wrong.