I think the reason why meta wants to federate is this:

• it helps with anticompetitive arguments, because it’s "open" and not controlled by meta alone
• some will refuse to use anything from meta, and threads users being able to communicate with them adds value
• it won’t hurt meta, because the majority will be using their app anyways
• it helps their image

I don’t think they’re doing it to "get more data" or to "take over the fediverse". There’s nothing worth taking over for them currently and since most people don’t care about the fediverse I don’t see it growing much either. Although I’d certainly like it if that were the case.

They can probably get the data already, it’s all openly available. Federating it’s basically all upside and no downside for them, but it’s not exactly the biggest priority to implement it, it‘s going to take some time.

I’m not saying it might not have a negative effect or that they care a lot for what’s currently there. They’ll certainly want to monetize threads sooner or later.