It’s definitely a combination of both but I think oil wealth is inherently destabilizing because it tends to be concentrated in areas which were not previously rich and densely populated (most of the world by area) and because the way the market works allows a relatively small number of people to be wealthy without much local support compared to, say, high-end manufacturing which require lots of skilled workers and local investment. Norway is basically the only example of a petrostate where the money is invested in the betterment of the entire country.

Yes. Not just the rest of the world wanting influence over the oil supply, resources. Natural resources have harmful effects: making currencies uncompetitive, corruption as people compete for a share of the wealth rather than creating new wealth..

https://moneyterms.co.uk/dutch-disease/

The middle east was literally roving bands of desert Bedouins and warring religious states long before fossil oil was known to be useful, let alone of major geopolitical importance.

Have people meddled since? Of course. Such is how power works. But you'd have to go back to Roman times to find a period of stability in the middle east, and the factors that led to that have nothing to do with Oil.

Norway and Botswana are good counterpoints here. I think its more about the fact that resource-rich countries naturally have a way for elites to stay in power longer than those without simply because they have enough money to go around to appease the populace they control. (An interesting test of this thesis would be how long Putin can stay in power now that they have to partially ration fuel due to Ukrainian refinery strikes)