A metro rail line can't transport a car, so point-to-point transit is out, as is any semblance of privacy. Why are you so quick to devalue these advantages?
If Musk can build a tunnel profitably, he should be able to do it, even if the opinion of people like you, mass transit would be preferable. Musk isn't willing to fund mass transit, but he is willing to fund a tunnel, so all you get by blocking the tunnel is neither mass transit nor a tunnel. Congratulations!