We don’t even know if there is a reason or not. If stuff like cause and effect are properties of the universe itself, they they don’t necessarily have to apply to it coming into existence (and if time and space are merely a part of the universe with no equivalent beyond, then the concept of it being caused by something runs into the issue of there being no time before it for a cause to occur and no place before it for that event to happen in).
There could be some equivalent of all those things of course, that the universe exists within, but we can’t just assume that.
I’m no AI bro, but I do think this concern is a bit overblown. The monetary value in art is not in simply having a picture of something, a whole infamous subset of “modern art” commands high prices despite being simple enough that virtually anybody could recreate it. A lot is simply in that people desire art created by a specific person, be it a painting that they made, or commissioning a still active artist to create something, or someone buying a band’s merch to support their work. AI simply does not have the same parasocial association to it. And of course, it doesn’t at all replicate the non-monetary value that creating something can give to someone.
I can, at most, imagine it getting integrated into things like advertising where one really doesn’t care who created the work; but even then there’s probably still value in having a human artist review the result to be sure of it’s quality, and that kind of art tends to add the least cultural value anyway.
That isn’t zero impact obviously, that kind of advertisement or corporate clip art or such does still pay people, but it’s a far cry from the end of creative human endeavor, or even people getting paid to be creative.