I think that's an overly reductive way of looking at it. Artists, are by their definition, creators of art. AI-generated "art" (it's not art at all in my eyes) is effectively a machine-based reproduction of actual art, but doesn't take the same skill level, time, and passion for the craft for a user to be able to generate an output, and certainly generates large profits for those that created the models.
So, imagine the scenario where you, an artist, trained for years to develop a specific technique and style, only for a massively funded company to swoop in, train a model on your art, make bank off of your skill while you get nothing, and now some rando can also create look-alikes (and also potentially profit from them - I've seen AI-generated images for sale at physical print stores and Etsy that mimic art styles of modern artists), potentially destroying your livelihood. Very little to be happy about here, to be frank.
It's less about competition and more about the ethical way to do it. If another artist would learn the same techniques and then managed to produce similar art, do you think there would be just as visceral of a reaction to them publishing their art? Likely not, because it still required skill to achieve what they did. Someone with a model and a prompt is nowhere near that same skill level, yet they now get to reap the benefits of the artist's developed craft. Is this "gatekeeping what's art"? I don't think so. Is this fair in any capacity? I don't think so either. Because we're comparing apples to pinecones.
All that being said, I do agree that the ship has sailed - the models are there, the trend of training on art AND written content shared openly will continue, and we're yet to see what the consequences of that will be. Their presence certainly won't stop me from continuously writing, perfecting my craft, and sharing it with the world. My job is to help others with it.
My hunch is that in the near-term we'll see a major devaluing of both written and image material, while a premium will be put on exceptional human skill. That is, would you pay to read a blog post written and thoroughly researched by Molly White (https://mastodon.social/@molly0xfff@hachyderm.io) or Cory Doctorow (https://pluralistic.net/), or some AI slop generated by an automated aggregator? My hunch is you'd pick the former. I know I would. As an anecdotal data point, and speaking just for myself, if I see now that someone uses AI-generated images in their blog post or site, I almost instantly close the tab. Same applies to videos on YouTube that have an AI-generated thumbnail or static art. It somehow carries a very negative connotation to me.