On the other, other hand, editing, etc., is a one time cost. And, as far as I can tell, <$10,000 per book.
Publishers, however, take their share per-copy. And, IIRC, the final profits are divided about 50/50 between author and publisher.
Charlie may be leaving a significant chunk of money on the table, given his popularity.
I wonder how much more work it would be to get a good relationship with a single priced editing service over a traditional publisher. Hey, maybe you could even get your agent to do that.