Affiliates as an industry standard demonstrate that you can run a profitable business with affiliates. In fact, there are affiliates for lots of businesses outside of online gaming nowadays. If businesses couldn't make money while affiliates existed, then affiliates would not exist.
Affiliates do not automatically get a chunk of deposits. Usually there are two options. They get paid a small lump sum for each new player, say $25-50. Or they get paid a % of the monthly generated rake (MGR) minus fees racked up by players.
I've survived for several years based on other players' willingness to play until they bust. But you can look at Las Vegas, Atlantic City, etc. for evidence of the sustainability of gaming.
Edit due to not being able to reply:
The rake sucks a lot for everyone. It turns small winners into small losers, or keeps consistent winners from being huge winners. It makes it so everyone gets less play for their dollar.
I know Pokertableratings has done some [very incomplete] tracking on player losses, but they don't have a record of every hand played.