There are other options: Fox, ABC News Radio, iHeart's 24/7 News, Associated Press, and Salem Media has 2 distinct news networks, SRN for religious stations and Townhall for conservative talk - but I would have thought CBS was one of, if not the, most financially healthy of the lot.
Apparently, in a NY Times article (I didn't read it, it was behind a paywall -- a guy on another radio forum mentioned it), it was reported that CBS Radio News made just $67,000 in revenue in one month, which was one of the drivers behind this decision. It's not really paying for itself apparently.
$67K a month, divided by 700 stations, that's an average of $96 dollars per station. Barrett Media had an article that said they were surprised that a news broadcast with as much reach couldn't make any money. Just the main CBS radio stations (I think they're owned by Audacy now, but they are still branded with CBS products -- KCBS, KNX, etc.) have millions of listeners combined. That's a lot of reach.
But the consensus seems to be that they simply can't sell enough time on the broadcasts to pay for the production. And unlike in the past, there really isn't any other CBS radio to prop the CBS Radio News up.