There is nothing accurate about describe it as "stolen", no one is depriving you of your art when training a model, like no human is depriving you of your art when learning from it.
While I wouldn’t describe AI art as stolen I do think it’s fair to claim there has been a loss of potential earning from the creative work that went into developing a style and the marketing that went into evangelizing/popularizing it.
The same applies when another human does it
Great difference in scale, humans cannot automate at nearly the level machines can. The law will have to account for this.