Why AI art is so controversial

It's not difficult of a question, it is in fact theft, and very predatory, as all artists who's work was scraped were never asked for permission.

Also, their work was copyrighted and used to create new images based on their hard work.

This isn't a question you can answer on your own from an outside point of view, you actually have to ask one of the millions of artists who's work was stolen, and they'll confidently tell you it's theft, and they'd rather an actual artist learn from them because it takes skill, rather than having their work dumped into a machine and profited off of in literally the millions, without permission.

AI art already HAS replaced jobs and will continue to do so if there's no legal repercussions. Midjourney is actually liable for a class action lawsuit for theft of copyrighted work, as they've profited over 101 million dollars from it