News departments are the loss leaders in the network TV business. They were once the foundation and the bedrock of network TV. That's simply not the case anymore.
I left the networks thirty years ago, but even in those days news didn't pay its own way. The rationale for the division was that it was part of our duty, as trustees of the public airwaves, to inform the public on the issues of the day. Those were the days when 'public interest, convenience, and necessity' was believed to mean just that.
The real downfall of networks new programs can be traced to the period when their news divisions ceased to be independent and instead became part of the entertainment division.