For the most part, the assumption of OP is absolutely spot on.
Nine times out of ten, if you have a high volume of traffic, AdSense is going to rank near the bottom when it comes to the amount of cash you get for every 1,000 views.
It’s almost guaranteed!
But—unfortunately, for a wide variety of reasons—not everybody can qualify for higher-paying display advertising networks.
Maybe you're in the wrong niche?
Maybe your audience is not as tightly defined as the platform would like?
Maybe your website doesn’t really fit the overall specialization of the higher-paying platform?
Also, there is such a thing as “the network branding effect.”
When large websites install the AdSense code so they can show AdSense ads, they are effectively partnering with Google—one of the largest brands on the internet.
Branding does have an effect on the overall perception visitors have of your website.
We all know that AdSense pays trash, but visitors don’t care about that; all they see is the “Ads by Google.”
This has an effect!
Also, don’t overlook the psychology of some of these people who own large, high-traffic websites.
At the back of their mind, they're probably thinking they’d rather partner with a tried and proven brand than a better-paying company that may not be around after a few years.
There's a lot of reasons why very busy websites would rather stick with AdSense.
A lot of it could also be simple inertia.
When you're stuck with something that delivers some sort of results, even if you're not completely thrilled with the results, you feel that it’s just too much of a hassle to make a change.
Why do you think millions of people still use the Bing search engine?
The answer should be obvious: it ships with Windows 10, and a lot of people don’t want to be bothered with making Google their default search engine.
