Comment by observationist

A big part of it is about the legal minefield if you presented any sort of real threat to Google. Nobody wants to wager billions in infrastructure and IP against Google or Apple or Microsoft, even if you could whip up a viable competing product in a weekend (for any given product.)

Part of it is also the ecosystem - don't threaten adtech, because the wrong lawsuits, the wrong consumer trend, the wrong innovation that undercuts the entire adtech ecosystem means they lose their goose with the golden eggs.

Even if Kagi or some other company achieves legitimate mindshare in search, they still don't have the infrastructure and ancillary products and cash reserves of Google, etc. The second they become a real "threat" in Google's eyes, they'd start seeing lawsuits over IP and hostile and aggressive resource acquisitions to freeze out their expansion, arbitrary deranking in search results, possible heightened government audits and regulatory interactions, and so on. They have access to a shit ton of legal levers, not to mention the whole endless flood of dirty tricks money can buy (not that Google would ever do that.)

They're institutional at this point; they're only going away if/when government decides to break it up and make things sane again.