I should have made more clear that this is a longer term strategy, and yes, indeed more expertise is needed in these industries. However, what these industries do is not rocket science, and can be reproduced over time.
My point is that SN sites could eventually do the conversion of that sort of traffic themselves, and gain higher CPM In the Long Run. This process would take years, but is rewarding in the end.
It doesn't always work that way in the real world. Some random company buying the ads at 10 cents CPM is not always getting traffic that is worth that much 100% of the time. By actually getting the entire revenue stream, the "child" company, and thus its parent would capture the true value of the traffic over a long period of time.
Spotting market inefficiencies like that should be really hard to do, considering that all of the mortgage brokers, for instance, already know their ROI on various sites, and the market will make it roughly equal everywhere over time.
This isn't about spotting temporary market inefficiencies, its about spotting long term ones that lurk beneath the surface.
In terms of real money, what comes out of it, is affiliate sales for companies + brand advertising.
Brand advertising is mostly worthless and gets talked up in value because it is even more worthless on national television.
But the kind of advertising that results in a sale is worth real money. Facebook either needs to start selling mortgages in house or develop better relationships with someone who sells mortgages.