Well, abusing their search dominance among other things like making ads indistinguishable from organic results and paid placement on verticals like shopping/hotels etc. was eventually going to pay out.
More details on how Google manipulated search rankings manually to make more money:
From http://www.wsj.com/articles/how-google-skewed-search-results...
>A previously undisclosed report by staffers at the Federal Trade Commission reveals new details about how Google Inc. manipulated search results to favor its own services over rivals’, even when they weren’t most relevant for users.
>In a lengthy investigation, staffers in the FTC’s bureau of competition found evidence that Google boosted its own services for shopping, travel and local businesses by altering its ranking criteria and “scraping” content from other sites. It also deliberately demoted rivals.
>For example, the FTC staff noted that Google presented results from its flight-search tool ahead of other travel sites, even though Google offered fewer flight options. Google’s shopping results were ranked above rival comparison-shopping engines, even though users didn’t click on them at the same rate, the staff found. Many of the ways Google boosted its own results have not been previously disclosed.
>One way Google favored its own results was to change its ranking criteria. Google typically ranks sites based on measures like the number of links that point to a site, or how often users click on the site in search results.
>But Marissa Mayer, who was then a Google vice president, said Google didn’t use click-through rates to determine the ranking for its own specialized-search sites, because they would rank too low, according to the staff report
>Instead, Google would “automatically boost” its own sites for certain specialized searches that otherwise would favor rivals, the FTC found. If a comparison-shopping site was supposed to rank highly, Google Product Search was placed above it. When Yelp was deemed relevant to a user’s search query, Google Local would pop up on top of the results page, the staff wrote.
>Other regulators have found similar practices. European antitrust authorities in 2013 said Google had a different, “specialized” search algorithm for ranking its own content.
>To bolster its own listings, Google sometimes copied, or “scraped,” information from rival sites. According to the FTC report, Google copied Amazon’s rankings of how well products were selling, then used that information to rank its results for product searches. Amazon declined to comment.
>While Google promoted its own results, it sometimes demoted rivals, the FTC staff found. For example, Google compiled a list of comparison-shopping sites and “demoted them from the top 10 web results,” staff wrote. According to the report, Google users in tests didn’t like the changes; only after Google tweaked its search algorithm at least four times, and changed the ranking criteria, did the new results get “slightly positive” feedback, the staff said.
>Google’s efforts paid off, the FTC found. It said Google’s maneuvers reduced Web traffic to rivals, and increased traffic to Google sites.