Scott Pressler's group and others doing the groundwork have been screaming for years now that they have been getting little to no help from the RNC.
Now I can't know it for certain, but it seems to me to be less from ineptitude and more by design. And the dropoff in incoming funds is a bonus, if the 'by design' theory holds.
But, if potential donors KNOW their money will be used to elect candidates that actually represent their interests, the donations might pour in again.