Generative ‘AI’ systems like Midjourney and ChatGPT are harmful to the artists (and I count all artists here, including writers) the underlying datasets are trained on because it directly aims to replace us.
It is harmful to the environment because of the server resources (electricity and water for cooling) needed.
It is also harmful to the people working in sweatshops for little to (literally) no money to do the 'learning’ for these systems (no, they are not actually 'learning’ by themselves, they sure as shit aren’t learning like humans and they are ABSOLUTELY not intelligent!!!)
You getting some nice lil picture of your blorbo out of it or the continuation of an abandoned fanfic is not worth the systematic exploitation and destruction of entire industries for the sole benefit of making rich assholes richer.