X terms of service:

You retain your rights to any Content you submit, post or display on or through the Services. What’s yours is yours — you own your Content (and your incorporated audio, photos and videos are considered part of the Content).

By submitting, posting or displaying Content on or through the Services, you grant us a worldwide, non-exclusive, royalty-free license (with the right to sublicense) to use, copy, reproduce, process, adapt, modify, publish, transmit, display and distribute such Content in any and all media or distribution methods (now known or later developed). This license authorizes us to make your Content available to the rest of the world and to let others do the same. You agree that this license includes the right for Twitter to provide, promote, and improve the Services and to make Content submitted to or through the Services available to other companies, organizations or individuals for the syndication, broadcast, distribution, promotion or publication of such Content on other media and services, subject to our terms and conditions for such Content use. Such additional uses by Twitter, or other companies, organizations or individuals, may be made with no compensation paid to you with respect to the Content that you submit, post, transmit or otherwise make available through the Services.

— https://x.com/en/tos/previous/version_13

Right: you retain ownership, and grant X certain rights to the content. Whether those rights include training AI on the data is legally and morally in dispute. X claims that right in its ToS, but a ToS isn’t law and may be legally invalid, and besides that the ToS system is famously broken in the US. Morally, I think it’s pretty clear that reasonable users did consent to their content being published as a tweet, and did not consent to X recreating the content as their own and taking credit for it.

When I signed up on Twitter in 2009 these ToS in no way implied using my tweets as training data. Nor they are worded explicitly that way now either.

Clearly does not include a provision to utilize Content for purposes of training an AI model.

In fact, they didn't include any purpose for their own use of the data and following GDPR thus cannot use the data at all. They did include purposes for other companies (syndication, broadcast, etc) which also doesn't include training of AI.

GDPR only covers europeans. Also I doubt very much it applies to publicly accessible data.

Err, yeah clearly does:

“you grant us a worldwide, non-exclusive, royalty-free license (with the right to sublicense) to use, copy, reproduce, process, adapt, modify, publish, transmit, display and distribute such Content in any and all media or distribution methods (now known or later developed).“

Not sure how anyone could defend that an AI model is not covered by this idea - such a model is easily covered by “distribution methods”.

Nope, the GDPR separates the action you perform on data from the purpose of such action. You need to collect consent for a purpose. X didn't state a purpose for why they would do any of these actions. Thus under EU laws their data collection is likely unlawful.

Adding a new purpose requires additional consent at least in the EU.

Well you might be right but their lawyers don’t seem to share your concerns.

Their lawyers may well share their concerns, but in the case of X, those lawyers may simply be getting ignored. This isn't a normal company.

I was under the impression ( and assumption ) that majority of mainstream social medias, literally, own everything that you post and archive it

They don’t. Mainly for legal reasons. They don’t want to responsible for stupid/libelous things users post.

Doesn’t appear to be the case https://x.com/en/tos/previous/version_13

Whoever owns the tweets is completely irrelevant.

If it is within his right to use this data for training purposes, then that's it.

And he is, btw.

And those terms were in place since way before he took over Twitter, btw, btw.

I cannot recall specifics but I thought this was very much a real thing with some sites? What you upload can be used by the publishing company.

IANAL disclaimer, but I believe social media companies very explicitly separate themselves from publishers for the purpose of not being responsible for what users post. They can't have it both ways.