The whole thing. They garner more revenue per search due to their critical mass of searchers and advertisers and can use this money to pay to be the default sea

The whole thing. They garner more revenue per search due to their critical mass of searchers and advertisers and can use this money to pay to be the default search option in browsers and mobile, to the point it would be loss making for any other search engine. Their analytics is present on many top sites so they can use browsing patterns to improve their results, on top of telemetry they get from Chrome. Perhaps only Facebook has something close to rivalling that kind of information. Googlebot and to an extent Bingbot are granted access to most sites that want to be crawled. Any new entrants have to jump through lots of hoops (e.g. Cloudflare) simply to crawl the same web they do. The UK's Competition and Market's Authority estimated that a credible competitor to Google would need to spend $20 billion just to be in a position to compete. There's a couple of companies that could realistically compete with their financial clout, one of them is paid ~$20billion a year to be the search default on iOS.