Good question. I have no idea ;-)

I guess it might not even matter. If what you're interested in is the best way to get more good books into the world rather than make the most money. From my experiences the folk in the publishing industry I've met are more interested in the former than the latter.

The issue I was trying to highlight though is that many people seem to ignore the "invest" part of what publishers do and see them as just people who print books. The publishers advance + the publisher/agent network are an investment. And with new authors an especially risky investment.

"Moreover, the best ROI for VC funded anything, seems to be an exit IPO. What would be the equivalent of an "IPO" for authors? A movie?"

I'm guessing getting a Terry Pratchett or a J. K. Rowling. That combination of talent and public zeitgeist that produces wads of cash.