Don't think they make them per se, it's part of the complexity of their strategies in the region.

Israel can't do the dirty work itself overtly (like invading Iraq or Syria). Not because it is clueless but because it is as much as a political & strategy battle as anything else. Saudi / Israel work with each other behind the scenes whenever it suits them, much like they worked with Iran. If Israel were to invade Syria or Lebanon the outcry would be immense and force other Muslim countries to go on the offensive. Whereas when it happens internally (Gaza / West Bank) nothing happens as israel has nukes.

But let's play out a scenario - if the US abandons the Saudi's, what happens to Saudi? It already funds most of the terrorism. Overthrow (Iraq, Libya) and destabilisation (Syria) has massively increased the terror threat in Western countries whether the action was right or wrong. So the risk is that the House of Saud gets replaced with a *worse* option and leads to Iran becoming the regional superpower. Iran gaining dominance, via any scenario as Shia's, is the worst possible outcome for the Saudi's / Qatari's.

I think this defines the US Saud relationship. Oil for global reserve dollar tradeoff - we keep our end of the bargain in return for you helping us in the region. Then you have to factor in the Syria / Iran / Russia alliance.