Long ago, In the early days of monetizing domain name traffic, there were only a few monetizing services, so whichever service you used had many advertisers, and PPC advertising was all the rage for advertisers... and a real money maker! Then more and more monetizing services appeared to get their share of the pot of gold! They very actively pursued advertisers, often offering less, to much less cost per click. As they did, the percentages of advertisers per service very rapidly slid down to where the shares of the available advertisers per monetizing service declined to where no service was doing anywhere near what it used to.
At the same time, many savvy advertisers started taking advantage of "direct navigation" by buying and registering domain names with keywords, and keyword phrases, that matched the purpose of their business and website, and either forwarded the "type-in" traffic to their website, or made very specific splash pages with links to their main website or websites. Developers also started buying and registering domain names with specific keywords, and keyword phrases, and made landing pages, directories, etc. where they sell advertising to each select group of very specific target businesses, niches, etc... even further severely cutting down the number advertisers per monetization service.
Lesson: Ya gotta keep on top of advancements and changes, and revise your business model accordingly. A VERY good example is: Many years ago, in the late 1980's, when I was general manager of a thriving company in Southern California, I did all the marketing, advertising, and even much of the related designing. I used to drive back and forth to an excellent little one-woman typesetting shop, when all typesetting was done manually on very expensive machines. I warned her as desktop computing was developing, that she should not "keep all her eggs in one basket"! However, she spent another like $24,000 for a newer machine, just before Microsoft and Apple came out with TrueType for the Mac and Windows, and very soon made all typesetting shops obsolete... a thing of the past... and she very soon LOST all her business, all her investment... and eventually, her home! Adapt, or perish!