It’s like saying robbing banks for a living isn’t sustainable and working at a bank is. That’s not exactly a stretch.
Regardless, I acknowledged the general issue. However I pointed out that doing so was not a technical necessity. If you base your worldview or actions around X implying Y but then it turns out that actually Y was merely a matter of convenience you're probably going to arrive at a wrong conclusion.
There's also the issue where you're emphatically calling it stealing without providing a clear criteria. The legal system as a whole has yet to conclusively resolve the various piracy accusations. The legality of consuming publicly available content remains quite controversial.
There’s a reason Reddit is making millions of dollars letting these companies mine their human generated content. You think OpenAI or anyone else would pay for that if they could just cyclically train on AI generated content???
I said nothing about that. Good synthetic data does not (typically) involve ML algorithms. Although that might be changing.
I'll politely suggest that you go read the literature before engaging further.
Reddit, Twitter, and similar are valuable because the data covers current events. Their content makes up a reasonably comprehensive timeline of the world at large. You don't need that to train a barebones functional model but it's certainly useful in order to train a knowledgeable one. Regardless, if they're charging for access it clearly isn't piracy so it doesn't seem like your original objection would hold any water in that case.
The tech world is obsessed with moving fast and breaking things, and you can't just do the same thing forever and expect it to always work.
It turns out that while these are all truisms, nobody wants to fix them. Developed countries are okay passing pigovian taxes, to a limited extent, to help fix these problems. Developing countries are even less interested in fixing these problems. It turns out that austerity is incredibly unpopular. Everyone wants to tell other people not to do the things they don't like but nobody wants to listen to what other people tell them not to do.
Just a reminder that Europe colonized Asia, Africa, and the Americas in the search for spices. Later on the interest changed to tea. Literally the only thing that Europe wanted was better tasting food and drink (initially at least.) By the time the potato had become widespread, they could have had enough calories to feed the continent, and yet the desire for flavor is what lead to untold misery for hundreds of years for millions of people.
We need to be realistic about what works and what doesn't. Austerity never wins.