From https://saudiembassy.net/agriculture-water -:
Today, Saudi Arabia exports wheat, dates, dairy products, eggs, fish, poultry, fruits, vegetables and flowers to markets around the world. Dates, once a staple of the Saudi diet, are now mainly grown for global humanitarian aid.
...
As a result, there has been a phenomenal growth in the production of all basic foods. Saudi Arabia is now completely self-sufficient in a number of foodstuffs, including meat, milk and eggs.
From https://saudiembassy.net/energy -:
In addition, with the discovery of deposits of precious and semi-precious metals, Saudi Arabia expects to become a major exporter of minerals in the coming decades.
...
Exploration projects over the past two decades have unearthed extensive deposits of precious and industrial minerals throughout the country. These include not only gold and silver, but also copper, tin, tungsten, nickel, chrome, zinc, lead, phosphates, iron ore, bauxite, potassium ore and even table salt.
Probably desalination plants run on Oil.
I am sure they can keep doing this but this is not a natural extension of any of their strengths. Their labor is over priced and mostly imported south asians, overburdened by heavy bureaucracy and lacking in the inputs of production.
Would you open a dairy farm in Namibia? If they really have to tighten their belts they will have to cut down on all these "extra-curricular" economic activities.
Data is from 2017. Single largest non-petro export being aluminum, at 0.51%.
" Most of the citizens simply don't work -- at all"
Where in the world you got this??
Iran has a theocratic regime, and gets a lot of oil revenue, but is a fundamentally diversified and surprisingly self-sufficient economy. They have factories, an educated population, and they produce a fair number of things other than oil. Agriculture exists (if not self-sufficient).
Saudi Arabia is oil rich. The princes are oil rich. The wealthy are oil rich. Normal people are oil rich. It's oil, all the way down.
The country simply doesn't produce anything else. Most of the citizens simply don't work -- at all. There's no plan B.
Iran can fall back to "hard times" and a pre-oil-wealth economy. SA can't. There's nothing else there except sand and starvation. They aren't going to "grin and bear it".