Recommend Arabs at War: Military Effectiveness, 1948-1991 (Studies in War, Society, and the Military) by Pollack

There are many reasons; one of them is that Arab forces often lie to their commanders so that they have very poor situational awareness, leading to a cascade of further poor decisions in war.

This is because you can and will be executed for failure.

Unfortunately, you can also be executed for being too competent, which can be seen as threatening to your superiors.

Also, maintenance. And sand. I hate sand.

There are many other factors and exceptions, depending on when and where.

The Gulf States are (IMO) facing the problem that they need a way to stay relevant as oil (or their geopolitical position where they get to buy security with oil) becomes obsolete but putting large-scale productive capital in their countries is going to automatically empower the people manning, operating, supplying and otherwise getting actual production out of said capital (which is to say the bourgeoisie and the proletariat). For a petrostate largely run along aristocratic lines that's a problem, because the new economic forces created by this transition will demand a political voice and Saudi aristocrats absolutely don't want to give them that. Industrialization was (with some twists and turns) good for European countries, but look what it did to European nobility. This is also why they don't create an effective army; without a strong, popular civilian authority (which none of them have) nothing will stop it from seizing power. Their big problem here is that you can't modernize in half-measures; you have to go all-in or not because the first step will drag you the rest of the way, probably violently if you resist. Other third world dictators for the most part have this problem too, but while they are forced to deal with it today Gulf monarchies are buying time with oil so they get to deal with it tomorrow. Fundamentally their behavior makes more sense when you realize that they're trying to thread a needle through a hole that doesn't exist.

And that's enough Karl Marx for one day I think. Remember, the answer is always communism.

and thier influence on trump is very limited compared to israel, and russia. they though they were getting a deal, but they dont seem to directly interact with politics, such as funding the actual campaigns or superpacs.