Because the Congress and the President don’t matter anymore.
The agencies do what they want because who’s going to stop them? Some silly elected politicians?
They don’t matter. The guys with the guns and the cool spy stuff do.
Everyone else is little people.
The IC is a de-facto COUNTRY with its own Personnel, policies and equipment, to some extent its own funding, and lies within America.
And it **occupies** America.
Neither party cares.