If your first printing does not sell out, you are done, finished, toast, and you will not get a second bite at the apple. The "real" publisher will use creative "Hollywood accounting" to screw you, I could list the ways but it would be a very long list. And after all that, you don't even own the rights to your own book, to reprint it yourself, if they printed too many and some were remaindered. This happens to 90% of first time authors, BTW.
The bad old publishing model was the same as a mother sea turtle: lay 100s of eggs and hope for a few best sellers. The rest die, so what? Tomorrow, another 100 manuscripts will arrive on their desk. 90% of authors who go this route wind up like 90% of the baby sea turtles, and the "real" publishers could not care less.
Amazon freed us from that horrible (for new authors) model.
When a "real" publisher can beat Amazon's 70% royalty, call me.
Sentinel sends me good accounting, and I have an agent. I don't expect a publisher to do much by way of advertising---that was in the "old days." My only gripe is that based on expectations of your last book, the publisher can vastly over-print, then you're stuck with a "loser" in their eyes, even if you sell really well.
For ex., my "Seven Events that Made America" sold well over 55,000---a number most publishers would salivate over. But because of the unrealistic phenomenal success of "A Patriot's History of the United States," the publisher printed over 110,000 copies! I made a very nice advance, but it will be a long time before I ever see another royalty on that. An author has zero control over the print run, which to me is the key.
I know of a self-published author who prices her books at $.99 and sells hundreds of thousands. But she works the social media, giveaways, and every other trick constantly. That's her living. It can be done and some people here (Travis McGee) do it much better than others (me).