You have big social divide:

The upper classes are all living in the Saudi’s welfare state even the most progressive/westernized part of this class are supporting the Monarchy (kind of like pre revolution iran’s socialists who hate the peasants more than the Shah because they despised the lower class for being uncivilized conservative).

And then you have the lower class who composed of the nomadic tribes that basically lives off grids and you have migrants workers who has zero rights.

I was going to write that it’s a mix of 3 things, but they’ve been pretty well elaborated already.

1. The Gulf State social model where the numerous relatives of the monarch constitute a sizable upper class, with everyone else being severely repressed

2. Oil money and fundamentalist ideologies keeping a lid on the figurative pressure cooker

3. Defense agreements and contracts first with the UK and then with the US. It is true for every monarchy in the region that without the American military alliance, they would crumble.

well they did have to have some DGSE commandos recite the shahada before dislodging rebels from the Grand Mosque back in 1979

They have a very cushy welfare state for Saudi nationals and a vast underclass of impoverished and effectively enslaved workers who are from other countries and have no local resources. If their workers get uppity they can be shipped home, beaten in to compliance, or just starved. If the Saudi nationals get uppity the royals can cut them off from that sweet, sweet oil money. And if you’re cut off you’re fucked because there’s nothing else to do in Saudi.

Think Immortan Joe in Mad Max - they control the water/oil/money

Look at how they consolidated power over the arabian peninsula in the first place (hint: it’s what the am stands for in Saudi Aramco) and then who remains the global hegemon from then to today.

Foreign aide and technology seemingly.

During the Cold War, socialism was spreading everywhere, including the Middle East. However, the US wanted to exploit the fact that socialism - on the surface - is an “atheistic” ideology. They tried pushing this aspect onto Muslim communities, making it seem like socialism is inherently incompatible with their beliefs, unlike capitalism which doesn’t care about what you believe. This meant the USSR was the biggest enemy because it was the largest socialist nation that was seeking to expand its influence

It was not just about ideology. The Middle East also produces a ton of oil which meant that if the USSR had influence there, they would control the flow of oil thus have a major advantage in war and production. The US spoke to the monarchs and secured a deal: constant oil and globally sold in USD in exchange for American military presence and weapons sales to stop socialism and SA becomes a regional power.

Various ME countries also disliked socialism and would help the US. But SA had the money and local influence to direct covert operations, and now they have every ounce of assistance available with the US.

Basically, the US helps the monarchs stay in control by keeping them happy to side with the US. Their shift towards China and the yuan is interesting. It’s opportunistic and I suspect they’ll go back to the US once they get pressured enough to satisfy SA’s demands. But right now both countries are trying to please the monarch so they continue to be propped up. They’re not phased by China’s hammer and sickle because they know China doesn’t care about regime change in the modern day. They just want the goods. However, the US wants to go scorched earth on anyone who doesn’t agree with them, and SA is wary of that as seen with its refusal to sanction Russia and getting sanctions themselves (thus going to China).