What ? KSA is hardly US government's enemy, on the contrary. KSA is US biggest ally in the middle east after Israel. KSA is not on the list of terrorist states in US and Saudi princes enjoy a wide access to politicians like the Bush family or the Clinton family which they actively finance. But it is interesting one would ever think it isn't the case.

TL;DNR: A stable oil market motivates everything. The KSA is a means to an end.

I think the real question is about the realpoltik of the American alliance with the House of Saud, versus Saudi Arabia as a whole. Lest we forget, 15 of the 19 were Saudis. Lest we forget, Saudi has the reputation of funding ultraconservative and politically reactionary movements around the world, that aren't exactly considered aligned with American political policies and values.

But that doesn't answer the questions about why the KSA is not listed as a terrorist financier and why the Saudi royal family enjoy easy access to the US government.

The first one is simple. If the US called it a terrorist financier, it would probably fatally damage the alliance. So what does the alliance give? Well, for the KSA it's a security guarantee. The US guarantees the acidity of the kingdom, and the Saudi family in particular against Iran. Also, the US gives political cover for maintaining a sphere of influence over the Arab world.

So what does the US get out of it? Well, two things. The primary goal is a stable supply of oil to the global market. (It's not about actual barrels of oil, but rather the global price of oil.)

Maintaining a reasonable supply of cheap oil is one of the two axes that all US Middle Eastern policy revolves. (The other is security for Israel.) The reason why oil is important is self-evident in a society reliant on petroleum products.

We should always remember that the initial reason why the US decided they had a national interest in Saudi Arabia was with the foundation of ARAMCO, which was originally known as California-Arabian Standard Oil.

So what's wrong with Iran? Iran? Well nothing at first. Iran, like Saudi Arabia was a an irrelevant backwater of international relations until the discovery of oil. After that, the Cold War intervened.

Well, the US pretty much poisoned the relationship with Iran when the CIA overthrew the democratic government and installed the autocratic Shaw, In an effort to stymie Soviet interests. When Kohmehni overthrew the Shaw, he lined up with the Soviets to put a needle in the Americans' eye. In response, the Americans strengthened the military relationship with KSA to counter Soviet influence in the region.

He seems to also be saying that the US is an enemy of Saudi Arabia. Otherwise "the enemy of my enemy is my friend" doesn't make sense.

Yes, I was saying that. But from the POV of Iran, not US.

As far as Iran is concerned SA attacked the US, Bin Ladin is from there, as were most of the attackers.

At a high level the US and SA governments are not enemies, but at a lower level (the people) it's not so simple.

No Saudi citizen I know hates America, heck they've embraced the American culture with awe and are the 4th largest student population in the US. American Fast food, American cars, etc are cherished and many American companies have flourished because of their establishments in Saudi Arabia.

Assumptions are harmful. Iranians on the other hand have a genuine reason to hate the US. Iran funds Hezbollah which have attached American interests in the past. It was Iranian-aligned militia that wrecked the American army in many battles in Iraq.

No. Its everything to do with common human empathy. Does that has nothing to do with the US?