The technology means nothing to them, as Arabs are notoriously poor maintainers of military hardware - it's all British and American technicians - so without us nothing flies.
So, our maintainers have jobs, along with spare parts manufacturers and logistics trains.
And Iran puckers up - that's a win-win.
Why do we need a Sunni counterweight to Iran?
ISIS is Sunni
Besides that, Sunnis and Shias have been at each other’s throats for over 1,000 years. Sometime one has had the upper hand in a region, sometimes the other.
Neither one likes us or any Western country or would lift a finger to help us in any way (unless they can get us to fight their wars for them). They’d rather see us dead.
What is our stake in an Islamic religious civil war?