Who actually pays the money in search arbitrage?
The advertiser pays. A business bidding on keywords in Google Ads or Microsoft Advertising is charged when someone clicks its ad on a partner page. The search engine keeps a share, the feed provider keeps a share, and the arbitrage publisher receives the rest. The publisher then pays the traffic source that supplied the visitor.
Follow one pound through the chain. The advertiser pays the search engine through Google Ads or Microsoft Advertising. The engine pays out TAC to its syndication partner. That partner, often a feed provider, applies its own revenue share before paying the sub-publisher. The sub-publisher has already spent money on ad spend at a traffic source to get the visitor in the first place.
This matters for understanding incentives. Everyone in the middle earns more when clicks rise, but only the advertiser cares whether the click became a customer. That is why search engines discount or claw back clicks that do not convert, and why advertisers were given an advertiser opt-out for partner inventory.