There's no conspiracy.
Mostly think tanks, policy circles, and White House wonks over every successive Internet-age administration. All segments of the U.S. government pay close attention to, among many people, geopolitical analysis of all stripes, who can help them understand how to remain the world hegemon. The U.S. frequently commissions studies by outfits like Booz Allen Hamilton on geopolitical matters (you can browse the "DoD Reading Room" to read plenty of the these thanks to FOIA requests[0]).
"Breaking them up would hurt the U.S." isn't just a lobbyist argument, it's deeply understood at all levels of the government. The White House absolutely understands that Silicon Valley is part of the U.S.'s soft power, draws plenty of international students to the U.S., and helps the U.S.'s cultural hegemony. It's not just about the most popular social networks and search engine "belonging to them" (though that's obviously important, and an advantage no rational nation would give up); Google and Meta's R&D spending are also huge elements of the U.S.'s "artificial intelligence dominance" over China, and the U.S. will never break them up simply because it sees AI-dominance as one of the most important elements of its geopolitical strategy.
It's easy to get the impression that the government mostly deals with domestic politics; but at its root, it is deeply and overwhelmingly concerned with fundamental strategic questions. The government cares deeply about U.S. universities remaining the world's best; about immigration remaining high (Republican administrations too) so that it can attract as much skilled labor as possible, grow the economy, compete with China's 1.4B population, and avoid an aging population that would decimate the economy for decades.
Policy debates "inside the government" bear very little resemblence to the TV version the American citizenry is obsessed with.
[0]: see, for example, "The Future of Europe", a 177 page evaluation of Europe's future economic, industrial, demographic, and political trends. https://www.esd.whs.mil/Portals/54/Documents/FOID/Reading%20... After you read it, you'll understand that the "policy debates" the masses are exposed to have very little resemblence with what preoccupies decisionmakers! The government, no matter the administration, is far more rigorous and strategic than people give it credit for.