EH and the NT spend millions of pounds every year on the restoration and preservation of structures - most of which are modern in comparison to Stonehenge and Silbury Hill.
I can't see any reason whatsoever in whingeing about money being spent on Stonehenge *as well as* any other site.
As I'm prepared to repeat ad nauseum, money being spent on Stonehenge is not stopping any money being spent on Silbury Hill.
Silbury Hill is a separate issue.
:o)
Baz