Haha, no Russia just sells and supports practically everyone else with "burgers"Who is Burger King and what are "Burgers" in this analogy. Because if you think the burgers are only weapons you're ignoring that the USA actually provides military assistance not just weapons. They have troops situated nearby and have in the past bombed sites in Yemen at the request of Saudi Arabia. They moved a carrier group into the region a couple of weeks ago. Burgers are a poor analogy for what the USA provides to Saudi Arabia. Which also brings us onto who you think Burger King is in this analogy? Russia? Because I don't see Russia arming a country that would like to see Iran overthrown or which aids IS in Syria on their doorstep. If Saudi Arabia wanted to buy burgers from Russia Burger King they'd have to settle down and behave 'cause otherwise they're just going to be kicked out of the restaurant. China? China doesn't do that.
Seriously, your analogy is hyper-reductive. Geopolitics is far, far more complicated than a Burger King analogy can provide. It is the backing of the USA that allows the Saudi regime to behave as it does and there aren't swap-in substitutes for that.
Also, I have never, ever been convinced of the argument that "if we didn't do it somebody else would". Especially not when applied to making money by propping up an oppressive regime that promotes terrorism in other countries.
Thanks for highlighting that politics are more complicated than burgers though.