Why are you entitled to other peoples work?

Do you really think you’ve never consumed data that was not intended for you? Never used copyrighted works or their elements in your own works?

Re-purposing other people’s work is literally what humanity has been doing for far longer than the term “license” existed.

If the original inventor of the fire drill didn’t want others to use it and barred them from creating a fire bow, arguing it’s “plagiarism” and “a tool that’s intended to replace me”, we wouldn’t have a civilization.

If artists could bar other artists from creating music or art based on theirs, we wouldn’t have such a thing as “genres”. There are genres of music that are almost entirely based around sampling and many, many popular samples were never explicitly allowed or licensed to anyone. Listen to a hundred most popular tracks of the last 50 years, and I guarantee you, a dozen or more would contain the amen break, for example.

Whatever it is you do with data: consume and use yourself or train a machine learning model using it, you’re either disregarding a large number of copyright restrictions and using all of it, or exist in an informational vacuum.

The act of learning is absorbing and using massive amounts of data. Almost any child can, for example, re-create copyrighted cartoon characters in their drawing or whistle copyrighted tunes.

If you look at, pretty much, any and all human created works, you will be able to trace elements of those works to many different sources. We, usually, call that “sources of inspiration”. Of course, in case of human created works, it’s not a big deal. Generally, it’s considered transformative and a fair use.

Not necessarily. There’s plenty that are open source and available for free to anyone willing to provide their own computational power.
In cases where you pay for a service, it could be argued that you aren’t paying for the access to the model or its results, but the convenience and computational power necessary to run the model.

Every work is protected by copyright, unless stated otherwise by the author.
If you want to create a capable system, you want real data and you want a wide range of it, including data that is rarely considered to be a protected work, despite being one.
I can guarantee you that you’re going to have a pretty hard time finding a dataset with diverse data containing things like napkin doodles or bathroom stall writing that’s compiled with permission of every copyright holder involved.

They’re not wrong, though?

Almost all information that currently exists has been created in the last century or so. Only a fraction of all that information is available to be legally acquired for use and only a fraction of that already small fraction has been explicitly licensed using permissive licenses.

Things that we don’t even think about as “protected works” are in fact just that. Doesn’t matter what it is: napkin doodles, writings on bathrooms stall walls, letters written to friends and family. All of those things are protected, unless stated otherwise. And, I don’t know about you, but I’ve never seen a license notice attached to a napkin doodle.

Now, imagine trying to raise a child while avoiding every piece of information like that; information that you aren’t licensed to use. You wouldn’t end up with a person well suited to exist in the world. They’d lack education regarding science, technology, they’d lack understanding of pop-culture, they’d know no brand names, etc.

Machine learning models are similar. You can train them that way, sure, but they’d be basically useless for real-world applications.