The preceding is about advertisers, and I don't see how they directly impact searchers? Maybe indirectly, but I don't see direct impact, or their revenue having anything to do with the search market share, the preceding stated:
This one's an interesting point to me... And leads me to the question:
If Searchers need the AdSense Ads to find what they are looking for, how good is Google in the first place? Or, IOW: How much better is Google as a search engine for the average searcher than any other search engine if searchers have to have a supply of ads on the results to find the answer they were looking for?
Personally, I've used both, and have been using Bing for quite a while now and still find what I need rather easily, but I'm also fairly good at searching, so my ability to use either may not apply to most users, but I can say I have not changed my queries too much to find similar results. I don't always find the same sites, but I do find the answer I need within the sites presented by Bing as easily as I did with Google.