It’s a common way to say someone was dupes by something, “they bought it” meaning they fell for it.

Mate, are you OK? I know what the phrase means and I'm struggling to see which part of my reply gave you the impression otherwise...

there was antitrust brought under the Biden admin. [link]

What is your argument here, exactly? That Trump appointing an anti-Big Tech person to lead the anti-trust section of the DOJ was... a bad thing... because Biden did stuff for anti-trust...? Hmm?

The point being GOP was only anti big-tech in rhetoric (...) He is either lying, or not paying attention.

Sigh...

Don't take it the wrong way, it's not an attack, just a statement of fact: people like you are the reason democracy is failing.

In most countries democracy has a 4-year turnover. One party comes in, says "we'll do X", gets to do their thing for four years, and then... It turns out that "X" takes 6 years to implement so people like you go "they lied to us, they didn't do X!". Now, the other party sees that and says "oh, trust us, we'll do Y" and "Y" is a bullshit non-issue or a non-solution to an actual issue, but it only takes 3 years to implement, which gives them a nice boost and a potential for re-election.

This creates a vicious cycle of parties becoming more and more populist, saying they'll "solve poverty by increasing minimum wage" (where the actual solution is massive changes in regulation and policy that would take a decade to implement), or "kick out immigrants to give back jobs to true XYZ" (where "true XYZ" don't want to do the jobs that immigrants take, and the solution, again, would be proper regulatory (and executive!) action, but that takes a decade or two to implement). Etc., etc.

Now, back to the point - yes, you're right. A lot of stuff happened during Biden's tenure. But A LOT of that stuff was started by Trump's administration, or the actions of the Trump administration opened the doors for a lot of what Biden did.

Here's a list of some of it:

DOJ Antitrust Lawsuit Against Google (2020)- Focused on Google’s deals with Apple and others to maintain default search engine status, thus harming competitors.

FTC Antitrust Lawsuit Against Facebook (December 2020)- To potentially break up Facebook by forcing it to divest those companies.

DOJ Antitrust Review of Big Tech (2019)- Laid groundwork for later actions, like the 2020 Google lawsuit.

FTC Tech Task Force (2019)- Re-examined acquisitions like Facebook’s of Instagram and WhatsApp.

Trump’s Executive Order on Section 230 (May 2020) to weaken legal protections that shield social media platforms from liability over user content and moderation decisions. - didn’t get much done as actual change would require Congressional action. But it intensified scrutiny of Big Tech.

Other indirect actions: Trump supported conservative-led Congressional hearings and investigations into Big Tech’s political power and influence or pushed the idea that companies like Amazon were harming small businesses and exploiting USPS