You mean if they falsify the search for both sides they make more money, as ironically spelt out in Google's original paper "The Anatomy of a Large-Scale Hypertextual Web Search Engine":

“We expect that advertising funded search engines will be inherently biased towards the advertisers and away from the needs of the consumers.”

“advertising income often provides an incentive to provide poor quality search results.”

“the better the search engine is, the fewer advertisements will be needed for the consumer to find what they want. This of course erodes the advertising supported business model...”

https://snap.stanford.edu/class/cs224w-readings/Brin98Anatom...

Note: they even explain why advertising funded search makes things worse for customers and for advertisers. Worse search finds more ads and thus more dollars, resulting in both worsening search results over time AND less value for ad money over time.