Even a Saturn 5 like monster of a rocket would need multiple launches to take the sort of material that would be needed for a Mars trip where it could be assembled in orbit and launch towards the planet...
The people speculating that this is some sort of system for delivering military forces anywhere on the planet rapidly are probably the closest to the truth... lets face it... no one in the US has deeper pockets to piss money away on useless stupid shit that likely wont work anyway than the US military.
The fact that it will be enormously expensive and will never work can be a secret... working with the F-35 so far...