That's not considered "big bucks", and secondly there is more demand for physicists than astronomers.
That's not true if you look outside of academia. Theoretical astrophysicists with computer experience don't have any trouble getting jobs as computer programmers, and observationalists that want to go into industrial also don't have too much trouble designing electro-mechanical instruments.
If he loves astronomy, then it won't matter -- he'll go for astronomy anyway. But just based on the number of jobs available and their salaries, vanilla physics beats astronomy.
For jobs outside of academia and the national labs, employers really don't care much what your field of interest was. All they care about is that you spent lots of time in front of a computer.